Accessory device with magnetic attachment

ABSTRACT

A magnetic attachment mechanism and method is described. The magnetic attachment mechanism can be used to releasably attach at least two objects together in a preferred configuration without fasteners and without external intervention. The magnetic attachment mechanism can be used to releasably attach an accessory device to an electronic device. The accessory device can be used to augment the functionality of usefulness of the electronic device.

CROSS REFERENCE TO RELATED APPLICATIONS

This U.S. patent application claims priority under 35 USC §120 and is aContinuation in Part of U.S. Design Patent Application No. 29/375,197,filed Sep. 17, 2010 and entitled “Cover” by Akana et al. Thisapplication also claims priority under 35 U.S.C. 119(e) to U.S.Provisional Patent Application No. 61/384,179, filed Sep. 17, 2010 andentitled “Apparatus and Method for Magnetic Attachment” by Lauder etal., both of which are incorporated by reference in their entirety forall purposes.

FIELD OF THE DESCRIBED EMBODIMENTS

The described embodiments generally relate to portable electronicdevices. More particularly, the present embodiments describe variousreleasable attachment techniques well suited for portable electronicdevices.

DESCRIPTION OF THE RELATED ART

Recent advances in portable computing includes the introduction of handheld electronic devices and computing platforms along the lines of theiPad™ tablet manufactured by Apple Inc. of Cupertino, Calif. Thesehandheld computing devices can be configured such that a substantialportion of the electronic device takes the form of a display used forpresenting visual content leaving little available space for anattachment mechanism that can be used for attaching an accessory device.

Conventional attachment techniques generally rely upon mechanicalfasteners that typically require at least an externally accessibleattaching feature on the electronic device to mate with a correspondingattaching feature on the accessory device. The presence of the externalattaching feature can detract from the overall look and feel of thehandheld computing device as well as add unwanted weight and complexityas well as degrade the appearance of the hand held computing device.

Therefore a mechanism for releasably attaching together at least twoobjects is desired.

SUMMARY OF THE DESCRIBED EMBODIMENTS

This paper describes various embodiments that relate to a system,method, and apparatus for releasably attaching an accessory to anelectronic device.

An accessory unit includes at least an accessory body and a magneticassembly pivotally connected to the accessory body. The magneticassembly includes at least a first plurality of magnetic elementsarranged adjacent one another in a first relative size order along afirst line and arranged according to a first polarity pattern ofalternating magnetic polarities, and a second plurality of magneticelements arranged adjacent to one another in a second relative sizeorder along the first line and according to a second polarity pattern ofalternating magnetic polarities.

A magnetic attachment method suitable for use with an accessory unit canbe carried out by providing a magnetic assembly where the magneticassembly includes at least a first plurality of magnetic elementsarranged adjacent one another in a first relative size order along afirst line and arranged according to a first polarity pattern ofalternating magnetic polarities and a second plurality of magneticelements arranged adjacent to one another in a second relative sizeorder along the first line and according to a second polarity pattern ofalternating magnetic polarities, wherein the first and second pluralityof magnetic elements cooperate to form a first magnetic sequence. In thedescribed embodiment, the method can be carried out by placing thesequenced magnetic assembly in proximity to a host unit, causing thecreation of a first magnetic surface by the host unit, the firstmagnetic surface being suitable for magnetic attachment, andmagnetically attaching the accessory unit and the host unit at anengagement surface corresponding to the magnetic surface.

An accessory unit in another embodiment includes at least an accessorybody having a first magnetic element and a second magnetic elementpivotally connected to the accessory body, wherein the second magneticelement magnetically attaches the accessory unit pivotally to a firstportion of a host unit and wherein the first magnetic element cooperateswith the second magnetic element to magnetically attach the accessorybody to a second portion of the host unit, wherein the first and secondmagnetic elements are independent of each other.

Other aspects and advantages of the invention will become apparent fromthe following detailed description taken in conjunction with theaccompanying drawings which illustrate, by way of example, theprinciples of the described embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be readily understood by the following detaileddescription in conjunction with the accompanying drawings, wherein likereference numerals designate like structural elements, and in which:

FIG. 1 is a simplified block diagram of an article and an electronicdevice that can be releasably attached to each other in a desired andrepeatable manner.

FIG. 2A is a simplified perspective view of an article that can bereleasably attached to an electronic device via a side magneticattachment system, in accordance with one described embodiment.

FIG. 2B shows the article and the electronic device of FIG. 2A attachedin accordance with the side magnetic attachment system.

FIG. 3A is a simplified perspective view of an article that isreleasably attachable to an electronic device via a top magneticattachment system in accordance with one described embodiment.

FIG. 3B shows the article and the electronic device of FIG. 3Amagnetically attached to each to each other to form a cooperating systemusing the top magnetic attachment system.

FIG. 4A is a simplified perspective view of an article that isreleasably attachable to an electronic device via the top and sidemagnetic attachment systems.

FIG. 4B shows a cooperating system of the attached article and theelectronic device shown in FIG. 4A in a closed configuration.

FIG. 4C shows the cooperating system of FIG. 4B in an openconfiguration.

FIG. 5 shows a top perspective view of an electronic device inaccordance with the described embodiments.

FIG. 6 shows another embodiment of a magnetic attachment feature.

FIG. 7A shows an electronic device in proximity to another object in theform of an accessory device having a magnetic attachment feature.

FIG. 7B shows a graphical representation of magnetic interaction betweenthe electronic device and the accessory device of FIG. 7A in accordancewith the described embodiments.

FIG. 7C shows a graphical representation of a cooperating system formedby the magnetic attachment of the accessory device and the electronicdevice as shown in FIGS. 7A and 7B.

FIG. 8A shows an embodiment of an attachment feature in an electronicdevice.

FIG. 8B shows an embodiment of an attachment feature in an accessorydevice corresponding to the attachment feature shown in FIG. 8A.

FIG. 9A shows a representative device attachment feature in an inactivestate.

FIG. 9B shows the representative device attachment feature of FIG. 9Aactivated by another magnetic attachment feature.

FIG. 9C shows the magnetic attachment feature in the inactive state inthe presence of magnetically active object.

FIG. 10 shows an implementation of a device attachment feature thatutilizes a leaf spring arrangement as a retaining mechanism.

FIG. 11A shows an embodiment of a keyed magnetic attachment system in aninactive state and a matching magnetic attachment system.

FIG. 11B shows the keyed magnetic attachment feature of FIG. 11Aactivated by the matching magnetic attachment system.

FIG. 12 shows a shifting position for the keyed magnetic attachmentfeature shown in FIG. 11A.

FIG. 13 shows a graph summarizing a magnetic attachment force versusrelative position of the keyed magnetic attachment feature.

FIGS. 14 and 15 show various embodiments of magnetic elements used inthe keyed magnetic attachment feature.

FIG. 16A shows a first perspective view of the electronic device in theform of a tablet device and the accessory device in the form of aprotective cover.

FIG. 16B shows a second perspective view of the electronic device in theform of a tablet device and the accessory device in the form of aprotective cover.

FIG. 17A shows a closed configuration of the cooperating system formedby the tablet device and protective cover shown in FIGS. 16A and 16B.

FIG. 17B shows an open configuration of the cooperating system shown inFIG. 17A.

FIG. 18 shows a top view of an embodiment of a segmented cover assembly.

FIGS. 19A-19C show a detailed view of a hinge span in accordance withthe described embodiments.

FIG. 20A shows a side view of the segmented cover assembly shown in FIG.18 attached to a tablet device.

FIG. 20B-20C show cross section views of the segmented cover assemblyand tablet device of FIG. 20A.

FIG. 21A shows a cross sectional side view of one embodiment of thehinge span of FIGS. 19A-19C magnetically attached to a housing having acurved surface.

FIG. 21B shows a cross sectional side view of another embodiment of thehinge span magnetically attached to a housing having a flat surface.

FIGS. 22A and 22B show cross sectional and perspective views of afixture used to assemble the hinge span in accordance with the describedembodiments.

FIG. 23 shows a side view of a segmented cover configured to support atablet device in a keyboard state.

FIGS. 24A and 24B show side and perspective views, respectively, of thesegmented cover configured to support a tablet device in a displaystate.

FIGS. 25A-25B show the segmented cover assembly configured as variousembodiments of a hanging apparatus.

FIGS. 26A and 26B show rear and front views, respectively, of a tabletdevice having a front and rear image capture device held by the handle.

FIGS. 27A-27C show a cooperating system of a segmented cover and tabletdevice configured to activate only uncovered portions of a display in apeek mode.

FIGS. 28A-28D show various exploded views of portions of a pivotinghinge assembly in accordance with the described embodiments.

FIG. 29 shows an exploded view of a top cover assembly in accordancewith the described embodiments.

FIG. 30 is a cross sectional view of the top cover assembly shown inFIG. 29 in place upon a tablet device highlighting the relationshipbetween an embedded magnet in the top cover assembly and a magneticallysensitive circuit in the tablet device.

FIG. 31A shows a cross sectional view of a hinge span magneticallyengaged with a corresponding device attachment feature in an activestate in accordance with the described embodiments.

FIG. 31B shows a cross sectional view of the device attachment featureof FIG. 31A in an inactive state.

FIGS. 32-33 shows perspective views of a device attachment featureincorporating a leaf spring as a retaining mechanism in accordance withthe described embodiments.

FIG. 34 shows a flowchart detailing a process of magnetic attachment inaccordance with the described embodiments.

FIG. 35 shows a flowchart detailing a process for activating a codedmagnetic attachment feature in accordance with the describedembodiments.

FIG. 36 shows a flowchart detailing a process for forming initiating amagnetic attachment in accordance with the described embodiments.

FIG. 37 shows a flowchart detailing a process for a peek mode operationin accordance with the described embodiments.

FIG. 38 shows a flowchart detailing a process for assembly of a hingespan in accordance with the described embodiments.

FIG. 39 shows a flowchart detailing process for determining aconfiguration of magnetic elements in a magnetic stack used in amagnetic attachment system in accordance with the described embodiments.

FIG. 40 is a block diagram of an arrangement of functional modulesutilized by a portable media device.

FIG. 41 is a block diagram of an electronic device suitable for use withthe described embodiments.

DETAILED DESCRIPTION OF SELECTED EMBODIMENTS

Reference will now be made in detail to representative embodimentsillustrated in the accompanying drawings. It should be understood thatthe following descriptions are not intended to limit the embodiments toone preferred embodiment. To the contrary, it is intended to coveralternatives, modifications, and equivalents as can be included withinthe spirit and scope of the described embodiments as defined by theappended claims.

The following description relates in general to a mechanism that can beused to attach together at least two suitably configured objects. In oneembodiment, this can be accomplished without the use of conventionalfasteners. Each of the objects can include an attachment featurearranged to provide a magnetic field having appropriate properties. Whenthe attachment features are brought into proximity with each other, themagnetic fields can cooperatively interact based upon their respectiveproperties, result in the objects magnetically attaching to each otherin a desired and repeatable manner. For example, due at least in part tothe cooperative nature of the interaction of the magnetic fields, theobjects can attach to each other in a pre-determined position andrelative orientation without external intervention. For example, thecooperative magnetic interaction can result in the objects self-aligningand self-centering in a desired orientation.

The objects can remain in the magnetically attached state if and until areleasing force of sufficient magnitude is applied that overcomes theoverall net attractive magnetic force. In some cases, however, it can bedesirable to detach the objects serially (along the lines of a zipper)in which case, the releasing force only need be of sufficient magnitudeto overcome the net magnetic attractive force of one pair of magneticelements at a time. Connectors such as mechanical fasteners are notrequired to attach the objects together. Furthermore, to prevent undueinterference to the magnetic interaction between the magnetic attachmentfeatures, at least a portion of the objects in the vicinity of themagnetic attachment features can be formed of magnetically inactivematerials such as plastic or non-ferrous metals such as aluminum ornon-magnetic stainless steel.

The objects can take many forms and perform many functions. Whenmagnetically attached to each other, the objects can communicate andinteract with each other to form a cooperative system. The cooperatingsystem can perform operations and provide functions that cannot beprovided by the separate objects individually. In another embodiment, atleast one device can be used as an accessory device. The accessorydevice can be magnetically attached to at least one electronic device.The accessory device can provide services and functions that can be usedto enhance the operability of the electronic device(s). For example, theaccessory device can take the form of a protective cover that can bemagnetically attached to the electronic device. The protective cover canprovide protection to certain aspects (such as a display) of theelectronic device while enhancing the overall look and feel of theelectronic device. The magnetic attachment mechanism used tomagnetically attach the accessory and the electronic device can assurethat the cover can only attach to the electronic device in a specificorientation. Moreover, the magnetic attachment mechanism can also assureproper alignment and positioning of the protective cover and theelectronic device.

The protective cover can include at least a hinge portion. The hingeportion can be magnetically attached to the electronic device using amagnetic attachment feature. The hinge portion can be pivotallyconnected to a flap that can be placed upon a portion of the electronicdevice to be protected. The protective cover can include electroniccircuits or other elements (passive or active) that can cooperate withelectronic elements in the electronic device. As part of thatcooperation, signals can be passed between the protective cover and theelectronic device that can, for example, be used to modify operations ofthe electronic device, operations of electronic circuits or elements ofthe protective cover, and so forth.

As an example, the electronic device can include a magneticallysensitive circuit such as a Hall Effect sensor and as such can detectthe presence of a magnetic field. The Hall Effect sensor can respond tothe presence (or absence) of the magnetic field by generating a signal.The signal can be used to alter an operating state of the electronicdevice. Accordingly, the protective cover can include a magnetic elementsuch as a permanent magnet having a magnetic field that can cause theHall Effect sensor to generate the signal. The magnetic element can bepositioned on the protective cover in a location that triggers the HallEffect sensor to generate the signal when the cover is placed on or inproximity to a surface of the electronic device. The signal can indicatethat the protective cover is in a predetermined position relative to theelectronic device that can result in a change in an operating state ofthe electronic device. For example, with the portion of the protectivecover having the magnetic element in proximity to the Hall Effectsensor, the magnetic field from the magnetic element can cause the HallEffect sensor to generate a signal. The signal can, in turn, be used toalter the operating state to one consistent with the display of theelectronic device being fully covered. On the other hand, when theportion of the protective cover having the magnetic element is removedto the point where the Hall Effect sensor no longer responds to themagnetic field of the magnetic element, then the Hall Effect sensor cangenerate another signal. The other signal can result in the electronicdevice entering another, different, operating state consistent with atleast a portion of the display being uncovered and viewable.

These and other embodiments are discussed below with reference to FIGS.1-40. However, those skilled in the art will readily appreciate that thedetailed description given herein with respect to these figures is forexplanatory purposes only and should not be construed as limiting. Forthe remainder of this discussion, a first and second object eachsuitably configured to magnetically attach to each other in accordancewith the described embodiments will be described. It should be noted,however, that any number and type of suitably configured objects can bemagnetically attached to each other in a precise and repeatable manner.In particular, for simplicity and clarity, for the remainder of thisdiscussion, the first object is presumed to take the form of anelectronic device and in particular a handheld electronic device.

FIG. 1 is a simplified block diagram of article 10 and electronic device12 that can be releasably attached to each other in a desired andrepeatable manner. More specifically, article 10 and electronic device12 can attach to each other at a pre-determined position and relativeorientation without external intervention and without the use ofmechanical fasteners. Article 10 and electronic device 12 can remainattached to each other if and until a releasing force is applied thatovercomes the engagement between them. In some cases, however, it can bedesirable to detach article 10 and electronic device 12 serially (alongthe lines of a zipper) in which case, a releasing force can be appliedthat can undo the engagement between article 10 and electronic device 12about one attachment component at a time. For example, an attachmentcomponent can include a suitably matched pair of magnetic elements, onein article 10 and a second in electronic device 12.

Electronic device 12 can take many forms. For example, electronic device12 can take the form of a portable electronic device. In some examples,the portable electronic device can include housing 15. Housing 15 canenclose and provide support for components of the portable electronicdevice. Housing 15 can also provide support for at least a large andprominent display occupying a substantial portion of a front face of theportable electronic device. The display can be used to present visualcontent. The visual content can include still images, visual, textualdata, as well as graphical data that can include icons used as part of agraphical user interface, or GUI.

In some cases, at least a portion of the display can be touch sensitive.By touch sensitive it is meant that during a touch event, an object(such as a finger, stylus, and so on) can be placed in contact with orin proximity to an upper surface of the display. The particulars of thetouch event (location, pressure, duration, and so forth) can be used toprovide information to the portable electronic device for processing. Insome embodiments, in addition to or in place of information beingprovided to the portable electronic device, information can be providedby the portable electronic device in a tactile manner using, forexample, haptic actuators. It should be appreciated however that thisconfiguration is by way of example and not by way of limitation as theelectronic device can be widely varied. In one example, the portableelectronic device is a tablet computer such as, for example, the iPad™manufactured by Apple Inc. of Cupertino, Calif.

Article 10 can be widely varied and can take many forms such as, forexample, an accessory or accoutrement of electronic device 12. As anaccessory, article 10 can be configured as a cover, a stand, a dock, ahanger, an input/output device and so on. In a particularly useful form,article 10 can take the form of a protective cover that can include amember, such as a flap, that can be positioned over the display of theportable electronic device. Like the electronic device 12, the article10 can also include housing 17 that can enclose and provide support forcomponents of the article 10.

Either one or both of article 10 and electronic device 12 can includeattachment features. For example, article 10 can include attachmentsystem 13 and electronic device 12 can include corresponding attachmentsystem 14. Attachment system 13 can cooperate with correspondingattachment system 14 to attach article 10 and electronic device 12 in areleasable manner. When attached to each other, article 10 andelectronic device 12 can operate as a single operating unit. On theother hand, in the detached mode, article 10 and electronic device 12can act separately, and if desired, as two individual parts. Attachmentsystems 13 and 14 can be configured in such a way that article 10 andelectronic device 12 can attach to each other in a desired andrepeatable manner. In other words, attachment systems 13 and 14 canrepeatedly align article 10 and electronic device 12 together such thatthey are consistently in a pre-determined position relative to oneanother.

The attachment features can be widely varied. The attachment can beprovided by various types of couplings including mechanical, electrical,static, magnetic, frictional, and/or the like. In one embodiment, theattachment cannot be seen from the outside of the article and/orelectronic device. For example, the article and device can not includeexternal visible attachment features that adversely affect the look andfeel or ornamental appearance (e.g., snaps, latches, etc.) but ratherattachment features that cannot be seen from the outside of the articleor device and thus do not affect the look and feel or ornamentalappearance of the article or device. By way of example, the attachmentfeatures can be provided by attraction surfaces that do not disturb theexternal surfaces of the article or device. In one embodiment, at leasta portion of the attachment features utilize magnetic attraction toprovide some or all of the attaching force.

The attachment systems can include one or more attachment features. Ifmultiple features are used, the manner in which they secure can be thesame or different. For example, in one implementation, a firstattachment feature utilizes a first attachment means while a secondattachment feature utilizes a second attachment means that is differentthan the first attachment means. For example, the first attachment meanscan utilize a friction coupling while the second attachment means canutilize magnetism. In another implementation, a first attachment featureutilizes a first attachment means while a second attachment featureutilizes the same or similar attachment means. For example, the firstand second attachment means can be provided by magnets. Although, theattachment means can be similar it should be appreciated that theconfiguration of the features can be different depending on the needs ofthe system. Further, any number and configuration of attachment meanscan be used.

In the illustrated embodiment, the attachment systems 13 and 14 eachinclude at least a first set of corresponding attachment features 13a/14 a and a second set of corresponding attachment features 13 b/14 b.Attachment feature 13 a can cooperate with corresponding attachmentfeature 14 a to attach article 10 and electronic device in a releasablemanner. In one particular implementation this is accomplished withmagnetic attraction. Further, attachment feature 13 b can cooperate withcorresponding attachment feature 14 b to further attach article 10 andelectronic device in a releasable manner. In one particularimplementation this is accomplished with magnetic attraction. By way ofexample, attachment features 13 a/14 a can be provided at a firstlocation while attachment features 13 b/14 b can be provided at a secondlocation.

In a specific example, attachment feature 14 a can, in cooperation withattachment feature 13 a, secure electronic device 12 to article 10. Inanother example, attachment feature 13 b can secure article 10 to theelectronic device 12 using attachment feature 14 b. It should be notedthat the attachment systems 13 and 14 of this example can be separate orthey can cooperate together to produce the attachment. If theycooperate, attachment features 14 a and 14 b correspond to or mate withone or more attachment features 13 a and 13 b. In any case, theattachment features in any of these examples can be accomplished throughmechanical, static, suction, magnetic attachment and/or the like.

The placement of the attachment systems and the attachment featureswithin the attachment systems can be widely varied. Regarding electronicdevice 12, attachment system 14 can be placed on front, back, top,bottom, and/or sides. Attachment features 14 a and 14 b can be placedany location within attachment system 14. Accordingly, attachmentfeatures 14 a and 14 b can be placed anywhere relative to the housingand/or the display. In one example, the attachment features 14 a and 14b can provide engagement along one or more of the sides of the housing(e.g., top, bottom, left, right). In another example, attachmentfeatures 14 a and 14 b can provide engagement at the back of electronicdevice 12. In yet another example, attachment features 14 a and 14 b canprovide engagement at the front (e.g., where, if present, a display islocated) of electronic device 12. In some cases, a combination ofattachment features can be located at different regions of electronicdevice 12 as for example at the sides and front. In one embodiment,attachment system 14 including attachment features 14 a and 14 b do notdisturb the surfaces of electronic device 12. Similarly; attachmentsystem 13 and in particular attachment features 13 a and 13 b do notdisturb the surfaces of article 10.

In accordance with one embodiment, the attachment features can includemagnetic elements. The magnetic elements can be configured to help inpositioning article 10 relative to electronic device 12 into a matingarrangement. The magnetic elements can further help to secure article 10and electronic device 12 into a mating engagement. It should be notedthat the engagement of article 10 and electronic device 12 can bereversed by the application of an appropriate releasing force thatallows article 10 and electronic device 12 to separate back intoindividual objects. However, the magnetic elements can permit thearticle 10 and electronic device 12 to subsequently resume the matingengagement without the requirement of fasteners of any sort, mechanicalor otherwise. In this way, the magnetic elements provide a repeatableand consistent engagement between article 10 and electronic device 12.

Article 10 and electronic device 12 can further include components 16and 18 respectively. Components 16 and 18 typically depend on theconfiguration of article 10 and electronic device 12 and can, forexample, be mechanical or structural components used to provide supportor they can be operational/functional components that can provide aspecific set of operations/functions. The components can be dedicated totheir respective devices or they may be configured for coupling withaspects of the corresponding article or device (e.g., wired orwireless). Examples of structural components can include frames, walls,fasteners, stiffeners, movement mechanisms (hinge), etc. Examples ofoperational components can include processors, memory, batteries,antennas, circuitry, sensors, display, inputs, and so on. Depending ontheir desired configuration, the components can be external (i.e.,exposed at the surface) and/or internal (e.g., embedded within housing).

FIGS. 2A and 2B are simplified perspective views of article 20 that canbe releasably attached to electronic device 22 via a magnetic attachmentsystem, in accordance with one described embodiment. Article 20 andelectronic device 22 can generally correspond to those discussed withregards to FIG. 1. In one embodiment, the magnetic attachment system canbe embodied as magnetic surface 24 (shown by broken lines or shading)and more particularly as magnetic surface 24 at the sides of electronicdevice 22. Magnetic surface 24 can provide a magnetic field that cancooperate with a corresponding attachment feature in article 20 whenplaced in proximity to one another. The magnetic field can establish anet magnetic attractive force that can pull article 20 and electronicdevice 22 together into the mating engagement along engagement surface26 as shown in FIG. 2B.

In other words, the magnetic field provided by magnetic surface 24 canhave properties such that the net magnetic attractive force betweenarticle 20 and electronic device 22 is substantially perpendicular toengagement surface 26. Moreover, the magnetic field can result in thenet magnetic attractive force between article 20 and electronic device22 being applied uniformly along engagement surface 26. In order torelease article 20 and electronic device 22, a releasing force can beapplied to the two conjoined objects in order to overcome a net magneticattractive force provided by the magnetic attachment system.

It also should be appreciated that although only one side wall is shown,in some cases different sidewalls and possibly a combination ofsidewalls may be used depending on the needs of the attachmentinterface. It should be noted that the use of magnetic attachmentprecludes the need for mechanical attachments such as fasteners.Moreover, the lack of mechanical attachments and the uniformity of theoverall magnetic attractive force can leave the surfaces of article 20and electronic device 22 undisturbed helping to create an appearance ofoneness by in which article 20 and electronic device 22 can appear as asingle, unified entity. The uniformity in appearance can improve theoverall aesthetic appeal of both article 20 and electronic device 22.

In one embodiment, a magnetic surface can be created by embeddingmagnetically attractable elements in the form of the magnetic attachmentfeature within the sidewalls of electronic device 22 and/or article 20.That is, the magnetically attractable elements can be disposed withinarticle 20 and electronic device 22 as for example within the housing ofelectronic device 22. In this configuration, the housing can be formedof non-magnetic material such as plastic or non-ferrous metal such asaluminum. In this way, magnetic force lines can be configured to workthrough the walls of the housing. The magnetic attachment features donot disturb the physical appearance of the external surfaces of article20 and electronic device 22. The magnetically attractable elements inarticle 20 and electronic device 22 can be arranged to produce magneticfields that can cooperate with each other to generate a magneticattractive force that attaches article 20 and electronic device 22together in the mating engagement. The magnetic attractive force beingconfigured to generate a magnetic attraction force normal to engagementsurface 26 between electronic device 22 and article 20.

The magnetic attractive force between corresponding magnetic elements inarticle 20 and electronic device 22 can also be uniformly applied alongengagement surface 26. The uniformity of the overall magnetic attractiveforce along engagement surface 26 can be a result of the uniformity ofthe separation distance between corresponding magnetic elements inarticle 20 and electronic device 22. The uniformity can also be a resultof the consistency of magnetic flux density between correspondingmagnetic elements in article 20 and electronic device 22. The uniformityof net magnetic attachment can be facilitated by the surfaces of article20 and electronic device 22 each forming a well matched fit to eachother. For example, one surface can be flat or have a concave geometrywhereas the other surface can have a matching conforming convexgeometry. In this way, by fitting tightly together, a separationdistance between each of the corresponding magnetic elements in article20 and electronic device 22 can be reduced to a minimum. The conformityof surface shapes can also enhance the overall look and feel of article20 and electronic device 22 by reducing or eliminating the appearance ofa seam at engagement surface 26. This seamless quality can provide anillusion of a single entity when article 20 and electronic device 22 areattached to each other.

In addition to enhancing the overall look and feel, the consistency ofthe separation distance between the magnetic elements can render theattachment force between article 20 and electronic device 22 uniformalong engagement surface 26. In this way, the engagement force can beuniformly distributed across engagement surface 26 preventing buckling,weak spots, and so on that might otherwise affect the overall integrityof the engagement between article 20 and electronic device 22.

FIGS. 3A and 3B are simplified perspective views of article 30 that canbe releasably attached to an electronic device 32 via magneticattachment system 34 and corresponding attachment system 36. It shouldbe noted that this particular embodiment is similar to the embodimentdescribed in FIGS. 2A, 2B except that the magnetic surfaces that werepreviously located at the side walls are now located on a face ofelectronic device 32 and, optionally, an opposing face on article 30.For example, in the case of an electronic device including a display,the magnetic elements of magnetic attachment system 34 can be embeddedbehind the display surface.

FIG. 3B shows article 30 and electronic device 32 magnetically attachedto each to each other to form cooperating system 38. As part of system38, electronic device 32 and article 30 can cooperate with each other toprovide features not available by article 30 or electronic device 32separately. For example, article 30 can take the form of a cover thatcan provide protective features. In one embodiment, protective cover canbe used to support and protect electronic device 32 while beingtransported or stored (e.g., cover the display surface). Due to thereleasable nature of the magnetic attachment between magnetic attachmentsystems 34 and 36, article 30 can be easily detached when electronicdevice 32 is to be used and subsequently re-attached when desired.

The placement of the magnetic elements can be such that only certainmagnetically sensitive elements within electronic device 32 are affectedby the magnetic field generated by the embedded magnetic elements. Forexample, a Hall Effect sensor can be used to detect whether or notarticle 30 is magnetically attached to and covering all or a portion ofthe display of electronic device 32 using the magnetic field generatedby a magnetic element located in article 30. On the other hand, amagnetically sensitive element in electronic device 32 such as a compassthat relies upon an external magnetic field (i.e., such as that providedby the Earth), must not be unduly affected by magnetic field linesgenerated by the embedded magnetic elements. Therefore, the magneticelements can be limited to those locations in electronic device 32positioned away from magnetically sensitive elements such as thecompass.

FIGS. 4A and 4C are simplified perspective views of article 40 that canbe releasable attached to electronic device 42 via a magnetic system 44.This embodiment is similar to that shown in FIGS. 2A, 2B and 3A, 3B inthat magnetic system 44 can include multiple magnetically attractableelements and that article 40 and electronic device 42 generallycorrespond to those mentioned in previous Figures. For example, one setof magnetically attractable magnetic elements 44 a can be placedrelative to a side of article 40 and electronic device 42 while a secondset of magnetically attractable elements 44 b can be placed relative toa face of article 40 and electronic device 42. As shown in FIG. 4B,cooperating system 46 can be formed by placing article 40 and electronicdevice 42 in proximity to each other such that magnetic elements 44 a onthe sides of article 40 and electronic device 42 magnetically attracteach other in addition to magnetic elements 44 b located at the face ofelectronic device 42 and article 40. The overall magnetic attractiongenerated at the side and face can be sufficient to retain article 40and electronic device 42 in a mating engagement to form cooperatingsystem 46.

In one embodiment, as shown in FIG. 4C, cooperating system 46 ispresented in an open configuration in which article 40 is used as acover for electronic device 42 that can be opened and closed. That is,article 40 can act as a protective cover of electronic device 42. Inthis embodiment, article 40 can include binding 48 that attaches alongthe side of electronic device 42 and flap 50 that attaches to the frontface of electronic device 42 and more particularly, top face 52. Topface 52 can correspond to a display. In one implementation, flap 50 canmove relative to binding 48. The moving can be widely varied. In oneexample, flap 50 can pivot relative to binding 48. The pivot can bewidely varied. In one example, the pivot can be enabled by a hingemechanism. In another example, the pivot can be enabled by a fold.Furthermore, the flap can be rigid, semi-rigid or flexible. In thismanner, article 40 can form an open configuration where flap 50 ispositioned away from electronic device 42 (display 52 can be viewed) anda closed configuration where flap 50 is positioned adjacent electronicdevice 42 (display 52 is covered as represented by closed embodiment ofFIG. 4B).

In one embodiment, binding 48 is only located on one side while flap 50is only located at top face 52. In so doing, the other surfaces ofelectronic device 42 are left exposed. As a result, the beauty of theelectronic device may be shown off while the article is attached to theelectronic device. Further, it may leave better access for I/O andconnectivity related functionality (e.g., buttons, connectors, etc.).

Although the purpose of the magnetic elements is similar, i.e., attacharticle to electronic device, it should be appreciated that thesemechanisms can widely vary. In some cases, the magnetic fields may beconfigured differently. By way of example, the side mounted magneticsurface may provide a first magnetic force and the front facing magneticsurface may provide a second magnetic force that is different than thefirst magnetic force. This may be in part due to different holdingrequirements as well as different surface areas, i.e., available space,and its effect on internal components of the electronic device. In oneexample, the side mounted magnetic surface provides a greater holdingforce for securing the article to the electronic device i.e., it is theprimary securing force while the front facing magnetic surface is thesecondary securing force.

In one example, flap 50 includes multiple sections that are semi-rigidand bend relative to one another so as to make the flap movable andflexible. In one embodiment, flap 50 can be folded into one or moredifferent configurations, and in some cases can be held in theseconfigurations using a magnetic system similar to what is describedabove. These and other embodiments will be described in greater detailbelow. Moreover, it should be appreciated that the described embodimentsare not limited to covers and that other configurations can be usedincluding for example as an accessory device used as a hangingapparatus, as a support mechanism for the electronic device to improveviewing the display and as a support mechanism for or inputting touchevents at a touch sensitive portion of the display, and so on.

The electronic device and article can take many forms. For the remainderof this discussion, the electronic device is described in terms of ahandheld portable computing device. Accordingly, FIG. 5 shows a topperspective view or electronic device 100 in accordance with thedescribed embodiments. Electronic device 100 can process data and moreparticularly media data such as audio, visual, images, etc. By way ofexample, electronic device 100 can generally correspond to a device thatcan perform as a smart phone, a music player, a game player, a visualplayer, a personal digital assistant (PDA), a tablet computer and thelike. Electronic device 100 can also be hand held. With regards to beinghandheld, electronic device 100 can be held in one hand while beingoperated by the other hand (i.e., no reference surface such as a desktopis needed). Hence, electronic device 100 can be held in one hand whileoperational input commands can be provided by the other hand. Theoperational input commands can include operating a volume switch, a holdswitch, or by providing inputs to a touch sensitive surface such as atouch sensitive display device or a touch pad.

Electronic device 100 can include housing 102. In some embodiments,housing 102 can take the form of a single piece housing formed of anynumber of materials such as plastic or non-magnetic metal which can beforged, molded, or otherwise formed into a desired shape. In those caseswhere electronic device 100 has a metal housing and incorporates radiofrequency (RF) based functionality, a portion of housing 102 can includeradio transparent materials such as ceramic, or plastic. Housing 102 canbe configured to enclose a number of internal components. For example,housing 102 can enclose and support various structural and electricalcomponents (including integrated circuit chips) to provide computingoperations for electronic device 100. The integrated circuits can takethe form of chips, chip sets, or modules any of which can be surfacemounted to a printed circuit board, or PCB, or other support structure.For example, a main logic board (MLB) can have integrated circuitsmounted thereon that can include at least a microprocessor,semi-conductor memory (such as FLASH), and various support circuits andso on. Housing 102 can include opening 104 for placing internalcomponents and as necessary can be sized to accommodate display assemblyfor presenting visual content, the display assembly being covered andprotected by protective layer 106. In some cases, the display assemblycan be touch sensitive allowing tactile inputs that can be used toprovide control signals to electronic device 100. In some cases, thedisplay assembly may be a large prominent display area that covers amajority of the real estate on the front of the electronic device.

Electronic device 100 can include a magnetic attachment system that canbe used to magnetically attach electronic device 100 to at least oneother suitably configured object. The magnetic attachment system caninclude a number of magnetic attachment features distributed within andin some cases connected to housing 102. For example, the magneticattachment system can include first magnetic attachment feature 108 andsecond magnetic attachment feature 110 located on different sides ofelectronic device 100. In particular, first magnetic attachment feature108 can be located in proximity to side wall 102 a of housing 102.Second magnetic attachment feature 110 can be located within opening 104near side wall 102 b of housing 102. In those embodiments whereelectronic device 100 includes a display with cover glass substantiallyFilling opening 104, second attachment feature 110 can be placed beneaththe cover glass.

The placement of first magnetic attachment feature 108 at side wall 102a can facilitate the use of magnetic attachment feature 108 tomagnetically attach electronic device 100 to another suitably configuredobject such as another electronic device or an accessory device.Accordingly, without loss of generality, first magnetic attachmentfeature 108 will henceforth be referred to as device attachment feature108.

The placement of second magnetic attachment feature 110, on the otherhand, can facilitate the use of second magnetic attachment feature 110to secure aspects of another device attached to electronic device 100 byway of device attachment feature 108. In this way, the overallattachment between the other device and electronic device 100 can bemore secure than attaching through first attachment feature 108 alone.Accordingly, and again without loss of generality, second attachmentfeature 110 will henceforth be referred to as securing attachmentfeature 110.

Although not expressly shown, it is understood that the various magneticattachment features of the magnetic attachment system can be located atany appropriate location of housing 102. For example, magneticattachment features can be located at an interior bottom surface ofhousing 102 or along sides 102 c and 102 d of housing 102.

As shown in FIG. 6, device attachment feature 108 and securingattachment feature 110 can each include one or more magnetic elements.In one example, device attachment feature 108 can multiple magneticelements that can magnetically interact with each other to providemagnetic field 112 (only a portion of which is shown). In other words,the properties (shape, field strength, and so on) of magnetic field 112can be based upon the interaction of the magnetic fields generated byeach of the magnetic elements. In this way, the properties of magneticfield 112 can be altered simply by arranging the properties (i.e.,physical layout, relative size, and constituent magnetic polarities) ofeach of the magnetic elements. For example, each of the magneticelements can have varying sizes and can be disposed along an axis. Inthis way, the magnetic properties of each of the plurality of magneticelements can act together to establish the overall properties ofmagnetic field 112.

In some cases, the portion of magnetic field 112 that is used in themagnetic attachment between device attachment feature 108 and anotherdevice can be enhanced with the use of a magnetic shunt (not shown). Themagnetic shunt can be formed of magnetically active material, such assteel or iron, and be placed in a position that causes magnetic fieldlines that would otherwise be directed away from the attachment regionto be at least partially re-directed towards the attachment region. There-direction of the magnetic field lines can have the effect ofincreasing the average magnetic flux density in the attachment region.

Device attachment feature 108 can operate in an active state as in wellas an inactive state. Magnetic flux density B₁₁₂ can equal or exceed amagnetic flux density threshold B_(threshold) inside the exteriorsurface of housing 102 but not outside in the inactive state. In otherwords, magnetic flux density B₁₁₂ of magnetic field 112 at an exteriorsurface of housing 102 is less than a magnetic flux density thresholdB_(threshold). Magnetic flux density threshold B_(threshold)representing a magnetic flux value below which magnetically sensitivedevices (such a magnetic strip on a credit card) can remainsubstantially unaffected. In addition, the presence of a magneticallyactive material (such as steel) in the region outside of electronicdevice 100 will not by itself trigger device attachment feature 108 totransition from the inactive state to the active state.

As noted above, when device attachment feature 108 is inactive, magneticflux density B₁₁₂ of magnetic field 112 at the exterior surface of side102 a of housing 102 is less than magnetic flux density thresholdB_(threshold). More particularly, with regards to device attachmentfeature 108, magnetic flux density B₁₁₂ can vary as a function ofdistance x (i.e., B=B₁₁₂ (x)) from the magnetic elements. Therefore,when device attachment feature 112 is inactive, magnetic flux densityB₁₁₂ (x) can satisfy Eq. (1).

B ₁₁₂(x=x _(o) +t)<B _(threshold.)  Eq. (1)

where

-   -   t is thickness of housing 102 at side 102 a, and    -   x_(o) distance from interior of side 102 a to the magnetic        elements.

When device attachment feature 108 is inactive, any magnetic fluxleakage in the near region outside of electronic device 100 (i.e.,B₁₁₂(x>x_(o)+t)) is low enough that there is little likelihood thatmagnetically sensitive devices in the near region are adverselyaffected. However, it should be noted that even in the inactive state,magnetic field 112 can have a value of magnet flux B₁₁₂(x=x_(o)+t) thatsatisfies Eq (1), and yet is sufficiently high to interact with themagnetic field of another device placed in relatively close proximitythereto. In this way, the other appropriately configured magneticattachment feature in the other device can be used to activate devicemagnetic attachment feature 108 even though Eq. (1) is satisfied.

The properties of magnetic field 112 can include at least fieldstrength, magnetic polarity, and so on. The properties of magnetic field112 can be based upon the combination of the magnetic fields from eachof the magnetic elements included in magnetic attachment feature 108 Thecombined magnetic fields can form in the aggregate magnetic field 112.For example, the magnetic elements can be arranged in such a way thatthe combination of the respective magnetic fields results in magneticfield 112 having desirable magnetic field properties (such as fieldstrength). For example, the combination of one arrangement of magneticelements can result in magnetic field 112 having characteristics (such apolarity and strength) that are for the most part symmetric about aparticular axis (such as a geometric center line).

On the other hand, the magnetic elements can be arranged in such a waythat the combination of the magnetic fields of the magnetic elements canresult in magnetic field 112 having at least one property that isanti-symmetric about the center line. For example, a magnetic element onone side of the centerline can be positioned with a North magnetic polepointing up whereas a corresponding magnetic element on the other sideof the centerline can be arranged with a South magnetic pole pointingup. Hence, the magnetic properties of magnetic field 112 can be adjustedin any manner deemed appropriate to provide a desired mating engagement.For example, the magnetic properties of magnetic field 112 can bemodified by arranging the magnetic elements in such a way that magneticfield 112 can cooperatively interact with another magnetic field (fromanother magnetic attachment system, for example). The cooperativeinteraction between the two magnetic fields can result in the twoobjects being magnetically attached to each other in a well-defined,precise, and repeatable manner.

The properties of magnetic field 112 can be stable. By stable it ismeant that the properties of the magnetic field can remain essentiallyunchanged for an extended period of time. Hence, a stable version ofmagnetic field 112 can be created using magnetic elements havingproperties that are essentially constant (or nearly constant) over anextended period of time or at least any changes in one component isoffset by a corresponding change in another component. The magneticelements can be physically arranged in a fixed or at least substantiallyfixed configuration with respect other magnetic elements. For example,the magnetic elements can each have fixed sizes and polarities arrangedin a specific order relative to each other providing the desiredproperties (shape, strength, polarity, etc.) of magnetic field 112.Hence, depending upon the properties and the nature of the magneticelements, the shape of magnetic field 112 can remain substantiallyunchanged over the extended period of time (such as the anticipatedoperating life of electronic device 100).

In some embodiments, however, the properties of magnetic field 112 canbe varied by modifying a magnetic or other physical property of at leastone of the magnetic elements. When at least one magnetic element hasmagnetic properties (e.g., a polarity or field strength) that can bemodified, the resulting magnetic field can also be modified.Accordingly, in some embodiments at least one of the magnetic elementscan be characterized as having dynamic-magnetic properties. By dynamicit is meant that at least one magnetic property, such as polarity, canbe modified. In this way, the magnetic field properties of the resultingmagnetic field can also vary. The resulting magnetic field, in turn, canalter the magnetic characteristics of magnetic field 112 that, in turn,can alter how the magnetic attachment system causes the objects tomagnetically attach to each other (alignment, orientation, centering,and so forth). An electromagnet is one example of such a magneticelement whose magnetic properties can be modified as desired. Otherexamples include a malleable non-magnetic substrate impregnated withmagnetic dopant (such as magnetite). In this way, the malleablesubstrate can be formed into a physical shape that can affect the natureof the magnetic field produced by the magnetic dopant material.

Turning now to other aspects of the magnetic attachment system, securingattachment feature 110 can include one or more of magnetic elements 116.When a plurality of magnetic elements is used, the arrangement of theplurality of magnetic elements 116 can be widely varied and canmagnetically interact with a cooperating feature on another device. Inone embodiment, the plurality of magnetic elements 116 associated withsecuring feature 110 can assist in securing at least a portion ofanother device otherwise attached to electronic device 100 by way ofdevice attachment feature 108.

At least some of the plurality of magnetic elements 116 can have a fixedsize and polarity (along the lines of a simple bar magnet) whereas otherof the plurality of magnetic elements 116 can have magnetic propertiesthat can vary (such as an electromagnet) while still others can beshaped to provide specific magnetic characteristics. For example, atleast one of the plurality of magnetic elements 116 can be positionedand shaped (if need be) to interact with a magnetically responsivecircuit included in the other device. Hence, the magnetically responsivecircuit can respond to the presence (or absence) of a particularmagnetic element(s) of securing feature 110. An example of themagnetically responsive circuit is described above with regards to theHall Effect sensor 118.

It should be noted that the magnetic field generated by magneticelements 116 should not extend so far that magnetically sensitivecircuits within electronic device 100 (such as Hall Effect sensor 118)are adversely affected. This is particularly important since themagnetic field is not generally contained within housing 102 since atleast a portion of the magnetic field must extend in the z direction inorder to interact with the magnetically active portion of other devices.Therefore, the magnetic field in {x,y} must be limited in extent toavoid magnetically sensitive circuits such as Hall Effect sensor 118 andcompass 120.

In a particular implementation, the magnetic elements of deviceattachment feature 108 can be grouped into distinct magnetic regions. Inthis way, the magnetic fields from the magnetic regions can superpose toform magnetic field 112. The magnetic regions can include variousmagnetic elements that can be arranged into groups represented bymagnetic elements 126 and 128. By grouping the magnetic element intoseparate magnetic regions, the ability of the magnetic attachment systemto provide a magnetic field having desired characteristics can besubstantially enhanced. Magnetic elements 126 and 128 can interact witheach other to form magnetic field 112. In the one embodiment, theinteraction can take the form of combination of magnetic properties ofeach of magnetic elements 126 and 128. In some cases, the arrangement ofmagnetic elements 126 and 128 can be related to each other in order toprovide magnetic field 112 with desired characteristics. For example,magnetic elements 126 can 128 can be arranged in such a way relative toone another that magnetic field 112 is anti-symmetric (or symmetric)about a horizontal center line of magnetic attachment feature 108. Inanother embodiment, magnetic field 112 can be anti-symmetric (orsymmetric) about a vertical center line of attachment feature 108. Instill another embodiment, magnetic field 112 can be anti-symmetric (orsymmetric) both horizontally and vertically.

FIG. 7A shows electronic device 100 in proximity to object 200 havingmagnetic attachment feature 202. Magnetic attachment feature 202 ofobject 200 can include magnetic elements each generating an individualmagnetic field that can interact with the other to form in the aggregatea resulting magnetic field. The resulting magnetic field can havemagnetic characteristics (such as field strength and shape) that caninteract with magnetic field 112 of electronic device 100 to attachelectronic device 100 and object 200 together in a well-defined,precise, and repeatable manner without mechanical fasteners and norrequire external assistance. It should be noted that magnetic field 208can be about 2500 Gauss whereas magnetic field 112 can be on the orderof about 1400 Gauss when device attachment feature 108 is inactive.

Object 200 can take many forms including an accessory, peripheral,electronic device or the like. In one embodiment, object 200 can takethe form of an electronic device along the lines of electronic device100. Accordingly, electronic device 100 and electronic device 200 can bemagnetically attached to each other using device attachment feature 108and magnetic attachment feature 202 to form a cooperative electronicsystem. The cooperative electronic system can be one in which electronicelements in electronic device 100 and corresponding electronic elementsin electronic device 200 cooperate with the other to perform functionsthat cannot be performed by either of the electronic devices separately.In one embodiment, information can be passed between electronic devices100 and 200.

More specifically, magnetic attachment feature 202 can include at leastmagnetic elements 204 and 206 each of which can generate magnetic fieldsthat cooperate with each other to provide magnetic field 208 (only aportion of which is shown). The properties of magnetic field 208 can bebased upon the interaction of each of the plurality of magnetic elements204 and 206. In this way, magnetic field 208 can have properties basedupon the physical layout, relative size, and constituent magneticpolarities of each of the plurality of magnetic elements 204 and 206.For example, magnetic elements 204 and 206 can be disposed along acenter line and have magnetic properties that superpose to providemagnetic field 208 with desired properties. Magnetic flux density B₂₀₈of magnetic field 208 of object 200 can vary as a function of distance x(i.e., B=B₂₀₈ (x)) from magnetic elements 204 and 206.

When object 200 takes the form of an electronic device such aselectronic device 100, then magnetic flux density B₂₀₈ satisfies Eq.(1). However, when object 200 takes the form of an accessory device,then unlike magnetic flux density B₁₁₂ of electronic device 100, whichsatisfies Eq. (1), magnetic flux density B₂₀₈ (x) of accessory device200 can satisfy Eq. (2).

B ₂₀₈(x=x ₁ +s)>B _(threshold)  Eq. (2)

where

-   -   s is thickness of housing 212 at side 212 a, and    -   x₁ interior separation distance.        In this way, accessory device 200 can magnetically interact with        electronic device 100 further removed from electronic device 100        than would otherwise be possible. Hence, accessory device 200        can be placed near but not necessarily close to electronic        device 100 in order for electronic device 100 and object 200 to        magnetically attach to each other in a well-defined,        predictable, and repeatable manner.

In addition to magnetic attachment feature 202, accessory device 200 canfurther include magnetic attachment feature 216 that can be used tointeract with securing attachment feature 110. Magnetic attachmentfeature 216 can include a variety of magnetically active components.Some of the magnetic elements can take the form of magnetic elementsarranged to cooperatively interact with corresponding magnetic elementsin securing attachment feature 110. Other of the magnetic element can bemore passive in nature in that they provide a mechanism for completing amagnetic circuit with magnetically active elements in securingattachment feature 110. An example of a magnetically passive element isa ferromagnetic material, such as, iron or steel, that can be interactwith a magnetic element actively providing an associated magnetic field.In this way, the ferromagnetic material can interact with the magneticfield to complete a magnetic circuit between the passive element inattachment feature 216 and the active element in securing attachmentfeature 110.

FIG. 7B shows that accessory device 200 can be used to provide supportfunctions and services for electronic device 100. By allowing a portionof magnetic field 208 having magnetic flux density B₂₀₈ satisfying Eq.(2) to extend into region 214, magnetic attractive force F_(net) betweendevice attachment feature 108 and accessory attachment feature 202 canbe created where net attractive force F_(net) satisfies Eq. (3a) and Eq.(3b).

F _(net)=(L _(total))·B ²/μ₀  Eq. (3a)

B/B ₀ =f(x _(scp))  Eq. (3b)

where

-   -   L_(total) is total surface area of magnetic elements    -   B is total magnetic flux density (B₂₀₈+B₁₁₂)    -   x_(scp) is separation distance between magnetic elements,    -   B₀ is magnetic flux density at surface of magnetic regions.

Net magnetic attraction force F_(net) due to the interaction of magneticfield 208 and magnetic field 112, attachment feature 202 can be used toactivate device attachment feature 108. Moreover, when device attachmentfeature 108 is activated, magnetic flux density B₁₁₂ now satisfies Eq.(4).

B ₁₁₂(x=x _(o) +t)>B _(threshold.)  Eq. (4) in active state.

This increase in magnetic flux density B₁₁₂ in region 214 can result ina substantial increase in net magnetic attractive force F_(net) betweenaccessory device 200 and electronic device 100. Moreover, since netattractive force F_(net) varies with total magnetic flux density B(B₂₀₈+B₁₁₂) and flux density B in general can vary inversely with theseparation distance (i.e., Eq. 3(b)), as electronic device 100 andaccessory device 200 approach each other and separation distance x_(scp)decreases to a limiting value consistent with physical contact ofelectronic device 100 and accessory device 200, the increase in netattractive force F_(net) can increase sharply in a relatively shortamount of time. This sharp increase in net attractive force F_(net) cancause the devices to quickly snap together in what can be referred to as“snapping into place” as shown in FIG. 7C showing cooperating system 300in the form of electronic device 100 magnetically attached to accessorydevice 200 along engagement surface 218. It should be noted that in arepresentative embodiment, the magnetic elements in device attachmentfeature 108 can be N52 type magnets whereas magnetic elements inattachment feature 216 can be N35 type magnets. Moreover, the netmagnetic attractive force can be on the order of about 10 newtons to atleast 20 newtons where it can require about 3 newtons to activate deviceattachment feature 108.

The overall magnetic attractive force F_(NET) between device 100 anddevice 200 at engagement surface 218 can be derived as the summation ofall the net magnetic attractive forces F_(neti) for all actively coupledmagnetic elements. In other words, the overall net magnetic attractiveforce F_(NET) satisfies Eq. (5).

F _(NET)=Σ₁ ^(n) F _(neti)  Eq. (5)

where F_(neti) is the net magnetic attractive force for each of ncomponents. In one embodiment, net magnetic attractive force F_(neti) issubstantially perpendicular to that portion of engagement surface 218intersected by magnetic field 112 and magnetic field 208.

In order to assure that overall magnetic attachment force F_(NET) isuniform along the engagement surface between device 100 and device 200,the separation distances between each corresponding magnetic element inattachment features 108 and 202 are well controlled. The separationdistance can be well controlled by, for example, shaping the magneticelements to conform to the shape of the devices. For example, if device100 has a spline (curved) shaped housing, the magnetic elements indevice 100 can be shaped to conform to the curved shape. In addition,the magnetic elements can be formed in such a way that the magneticvectors of corresponding magnetic elements align with each other. Inthis way, the magnitude and direction of the net magnetic attractiveforce can be controlled as desired.

One result of the aligning of the magnetic vectors is that the directionof the net magnetic force between each magnetic element can be wellcontrolled. Moreover, by reducing the separation distance betweencorresponding magnetic elements to a minimum, the net attractivemagnetic force F_(neti) between each magnetic element can be maximized.In addition, maintaining a substantially uniform separation distancebetween the various magnetic elements, a correspondingly uniformmagnetic attachment force can be provided along engagement surface 218.Moreover, by appropriately adjusting the corresponding magnetic vectors,F_(net) can be applied normally to the engagement surface.

In addition to minimizing the separation distance between correspondingmagnetic elements, the magnetic flux density between the correspondingmagnetic elements can be increased by using magnetic shunts. A magneticshunt formed of magnetically active material such as iron or steel canbe placed on or near a magnetic element having the effect of directingmagnetic flux lines in a desired direction. In this way, for example,magnetic flux lines that would otherwise propagate in a direction awayfrom a corresponding magnetic element can be partially re-directedtowards a desired direction, such as towards a magnetic attachmentregion between the devices thereby increasing the overall magnetic fluxdensity. Hence, increasing the available magnetic flux density betweenthe magnetic elements can result in a substantial increase in the netmagnetic attractive force.

FIG. 8A shows an embodiment of attachment feature 110. In particular,attachment feature 110 can be part of housing 102. In particular,attachment feature can include magnetic elements 402 that can be mountedto ledge 404 of housing 102 Magnetic elements 402 can be widely varied.For example, magnetic elements 402 can be spatially arranged as an arrayon ledge 404 to be used to attach and secure at least a portion of anaccessory device to a particular aspect of electronic device 100. Forexample, when the accessory device takes the form of a flap, themagnetic elements 402 can be used to magnetically secure the flap toelectronic device 100 to cover at least a portion of a display. The sizeand shape of the array can also be widely varied. In the embodimentshown in FIG. 8A, the array can be rectangular and sized to encompass asubstantial portion of ledge 404.

FIG. 8B shows a plurality of magnetic elements 410 that can beincorporated into an accessory device as part of attachment feature 216.Some but not all of the plurality of magnetic elements 410 cancorrespond to magnetic elements 402 and be used to magnetically attachaccessory 200 to electronic device 100. In another embodiment, all ormost of the plurality of magnetic elements 410 can be used to secureportions of accessory device 200 together to form other supportstructures that can be used in conjunction with electronic device 100.In one embodiment, magnetic element 414 can be used to activate amagnetically sensitive circuit such as Hall Effect sensor 118.

FIGS. 9A-9C show representative magnetic attachment feature 500 inaccordance with a described embodiment. Magnetic attachment feature 500can, for example, correspond to device attachment feature 108 shown FIG.6 and FIGS. 7A-7C. In the inactive state, the magnetic elements withinmagnetic attachment feature 500 can be positioned away from housing 102to minimize the magnetic field lines that propagate through 102. On theother hand, in the active state, the magnetic elements can move towardshousing 102 in order to increase the number of magnetic field lines thatpropagate through housing 102 thereby satisfying Eq. (2).

The manner in which the magnetic elements moves can be widely varied.For example, the magnetic elements can rotate, pivot, translate, slideor the like. In one example, the magnetic elements can be positionedwithin a channel that allows the magnetic elements to slide from a firstposition corresponding to the inactive state to a second positioncorresponding to the active state.

In the particular embodiment shown in FIGS. 9A-9C, attachment feature500 can include magnetic element 502 having magnetic properties that canremain stable over a period of time. For example, it can be desired thatthe magnetic attachment properties remain stable over the expectedoperating life of electronic device 100. In this way, the magnetic fieldformed by the interaction of the magnetic fields of each of the magnetswill also remain stable. The stability of the magnetic field can resultin a very repeatable attachment process. This repeatability isparticularly useful when electronic device 100 undergoes numerous andrepeated attachment cycles (attach/detach) with other appropriatelyconfigured objects such as accessory device 200 that requires aconsistently accurate placement.

In the representative embodiment shown, magnetic element 502 can takemany forms. For example, magnetic element 502 can take the form of anumber of magnets arranged in a specific order and configuration havingstable magnetic properties (such as polarity and intrinsic magneticstrength). However, in order to satisfy Eq. (1) when magnetic attachmentfeature 500 is inactive, magnetic element 502 must remain at leastdistance x=(x₀+t) from the exterior of housing 102. In other words, inorder to satisfy Eq. (1), the dimensions of device attachment feature500 must take into consideration at least the magnetic properties andphysical layout of magnetic element 502.

Accordingly, magnetic element 502 can be attached to retaining mechanism504 arranged to exert retaining force F_(retain). Retaining forceF_(retain) can be used to retain magnetic element 502 at a positionwithin device attachment feature 500 resulting in little or no magneticflux leakage outside of electronic device 100 (i.e., Eq. (1) issatisfied) when device attachment feature 500 is inactive. In oneembodiment, retaining mechanism 504 can take the form of a springarranged to provide retaining force F_(retain) according to Eq. (6):

F _(retain) =k·Δx  Eq. (6)

where

-   -   k is spring constant of retaining mechanism 504, and    -   Δx is spring displacement from equilibrium.

For example, FIG. 9B shows representative magnetic attachment feature500 in an active state. By appropriately configuring magnetic element502 and those in accessory attachment feature 204, the resultingmagnetic interaction of the magnetic field of magnetic element 502 andthat generated by accessory attachment feature 204 can create a netattractive magnetic force at least as great as that required to activatemagnetic attachment feature 500. In other words, the net attractivemagnetic force can have a magnitude at least that of activation forceF_(act) satisfying Eq. (7) thereby overcoming retaining force F_(retain)causing magnetic element 502 to move from the inactive position (i.e.,x=0) to the active position (i.e., x=x₀),

F _(act) ≧F _(retain)(Δx=x _(o))  Eq. (7).

However, only another magnetic attachment feature that generates amagnetic field having properties that “match” the magnetic fieldproperties of magnetic element 502 can activate magnetic attachmentfeature 500. Therefore, as shown in FIG. 9C, the presence of object 506formed of magnetically active material (such as steel) located at theexterior surface of housing 102 (i.e., x=x₀+t) cannot activate magneticattachment feature 500. More specifically, in one embodiment, the netmagnetic attractive force generated between object 506 and magneticattachment feature 500 less than 2 NT, whereas activation force F_(ACT)can be on the order of about 3 NT.

More specifically, in order to transition from the inactive to theactive state, the magnetic force created between magnetic element 502and object 506 must be greater than activation force F_(act). However,since the magnetic flux density of the magnetic field generated bymagnetic element 502 at the exterior surface of housing 102 is less thanB_(threshold) any magnetic force generated between object 506 andmagnetic element 502 is substantially less than F_(retain) and thereforefails to satisfy Eq. (7). Hence, magnetic element 502 remains fixed inplace at about x=0 and magnetic attachment feature 500 cannot undergothe transition from the inactive to the active state.

It should be appreciated that the spring can be widely varied. Forexample, it may vary depending on the type of movement. Examples includetension, compression, torsion, leaf and the like. In one particularimplementation, leaf springs are used.

It should also be noted that in some embodiments, magnetic element 502can be fixed in such a way that no spring is needed. In theseembodiments, although Eq. (1) may not be satisfied, it can nonethelessbe a practical arrangement.

FIG. 10 shows an embodiment of device attachment feature 600 inaccordance with one embodiment of the present invention. Attachmentfeature 600 can correspond to element 208 in FIG. 6 and FIGS. 7A-7C.This embodiment is similar to the embodiment shown in FIGS. 9A-9C exceptthat instead of a single mechanism, multiple mechanisms and moreparticularly a pair of mechanisms in the form a magnetic element 602 andmagnetic element 604 are used. In particular, FIG. 10 shows deviceattachment feature 600 in the active state. More specifically, spring606 attached to magnetic element 602 and spring 608 attached to magneticelement 604 are each extended by distance Δx.

In this system, the two mechanisms cooperate to form the magnetic field.They can move independently or they can be connected together and moveas a unit. The spring forces and the magnetic forces can vary. Forexample, system can be symmetric or asymmetric. The arrangement ofmagnetic elements may be similar or different. Again being symmetric orasymmetric. The configuration may depend on the needs of the system.

The magnetic attachment system can take many forms each of whichprovides for a repeatable and precise magnetic attachment mechanism thatcan be used to attach multiple suitably configured objects together.

FIGS. 11A-11B show a specific implementation of device attachmentfeature 108 in the form of device attachment feature 700 in accordancewith one embodiment. The device attachment feature can correspond toelement 108 shown in FIG. 6 and FIGS. 7A-7C. In some cases, deviceattachment feature 700 can be used in conjunction with springs 606 and608 as shown in FIG. 10. As shown in FIG. 11A, device attachment feature700. In particular, device attachment feature 700 is shown in theinactive state having magnetic elements in the form of magnetic assembly702 that can be enclosed within an enclosure. In this way, a retainingmechanism (not shown) attached to magnetic assembly 702 can exertassociated retaining force F_(retain). Retaining force F_(retain) can beused to maintain magnetic assembly 702 at a position consistent withdevice attachment feature 700 being in the inactive state (i.e.satisfying Eq. (1)).

Magnetic assembly 702 can each include individual magnets. In thedescribed embodiment, the individual magnets can be arranged in astructure in which the polarities of the magnets can be oriented to forma coded magnetic structure. The coded magnetic structure can be formedof a sequence of magnetic polarities and in some cases magneticstrength. In other words, the sequence of magnetic polarities can berepresented, for example, as {+1, +1, −1, +1, −1, +1, −1, −1}. For thisparticular example, “+1” indicates the direction and strength of themagnet. Hence, a positive sign “+” can indicate that the correspondingmagnet is aligned having a magnetic vector in a particular direction, anegative sign “−” can indicate a magnetic vector in an oppositedirection and “1” indicates a strength of one unit magnet.

When a plurality of magnets of the same polarity are placed next to eachother, the magnetic fields from each of the plurality of magnets cancombine such that the plurality of magnets can be considered equivalentto a single magnet, the single magnet having the combined properties ofthe plurality of magnets. For example, the coded magnetic sequence {+1,+1, −1, +1, −1, +1, −1, −1} representing eight individual magnets can beconsidered equivalent to the coded magnetic sequence {+2, −1, +1, −1,+1, −2} embodied as an array of six individual magnets. In oneembodiment, the magnets in a first and last position can possess thesame magnetic strength as the other magnets in the array but twice theirrespective size. On the other hand, the magnets in the first and lastposition can have about the same size as the other magnets but possesstwice the magnetic strength of the other magnets. In any case, theequivalency of magnetic properties can provide for a more compact codedsequence of magnets. The smaller size can help reduce weight as well aspreserve the amount of valuable internal real estate required to housethe magnetic attachment feature. In addition, since magnetic fluxdensity is directly related to that area through which magnetic fieldlines propagate, as the area through which a given magnetic fluxpropagates decreases, the resulting magnetic flux density increases.

In one embodiment, magnetic assembly 702 can include individual magnets712 a, 712 b, and 712 c having relative sizes of 2L, 1L, and 1L,respectively, where “L” represents a unit length. It should be notedthat as discussed above a magnet having a relative size of “2L” can beembodied as either a single magnet having a physical length of “2L”, twomagnets side by side each having a length “1L” with the magnetic polesaligned with each other, or a magnet of unit length L having twice themagnetic strength of the other magnets. Accordingly, for the remainderof this discussion, with regards to the terms 2L and 1L, “L” canrepresent a unit length and the relative strength of the magnet can berepresented by the associated digit. For example, a magnet having arelative magnetic strength of “1” but a length of “2L” can be consideredequivalent to a magnet having a relative strength of “2” and a length of“1L”. In this way, both the relative magnetic strengths, and orientationcan be used to form the coded magnetic structure.

For example, magnet 712 a can have an overall length of approximatelytwice that of magnets 712 b or 712 c. On the other hand, magnet 712 acan have the same length as magnets 712 b and 712 c but have an inherentmagnetic strength twice that of magnets 712 b and 712 c. In yet anotherembodiment, magnet 712 a can be an equivalent magnet formed of two (ormore) constituent magnets having their respective polarities aligned.

In one embodiment, magnets 712 a, b, c can each be spaced apart fromeach other a predetermined distance. For example, in one implementation,the magnets can be spaced equidistant from each other. This spacing is,of course, predicated upon the desired magnetic properties of themagnetic field generated. In another embodiment, those magnets havinganti-aligned polarities can be magnetically attached to each other. Inthis way, the magnetic bond formed between the adjacent magnets can beused to maintain the integrity of the sequence of magnets in themagnetic assembly. However, those magnets having aligned polarities mustbe held together by an externally applied force to overcome therepulsive magnetic force generated between the two aligned magnets.

In addition to size and positioning, the magnetic polarities of magnets712 a, b, c can be selected based upon the desired properties of themagnetic field generated. In the embodiment shown, however, the magneticelements are magnetically coupled to each other end to end therebyreducing the amount of space required and increasing the magnetic fluxdensity by reducing an overall region in which the magnetic field linesare propagated.

In particular, magnetic assembly 702 can have a specific magneticpolarity pattern set in which each of magnets 712 a, b, c are orientedin such a way that their N or S magnet poles are aligned (oranti-aligned) in a particular manner. For example, the magnets inmagnetic assembly 702 can be arranged to form first coded magneticstructure (+1, −1, +1) in which the magnetic poles of magnets 712 a, b,c are aligned according to first magnetic polarity pattern {P1, P2, P1}by which it is meant that the magnetic pole of magnet 712 a isanti-aligned relative to magnet 712 b which in turn is anti-aligned withmagnet 712 c.

Magnetic assembly 702 can also include individual magnets 714 a,b,c andhaving relative sizes of 1L, 1L, and 2L, respectively. Furthermore,magnets 714 a, b, c can be arranged to have their respective magneticpoles aligned in accordance with second magnetic polarity pattern {P2,P1, P2} that is the inverse (or complement) of first magnetic polaritypattern {P1, P2, P1}. In terms of coded magnetic structure, magnets 714a,b,c can be aligned according to second coded magnetic sequence {−1,+1, −1} that is the inverse, or complement, of first coded magneticstructure {+1, −1, +1}. This anti-symmetric relationship between magnets712 a,b,c and 714 a,b,c provides a magnetic field that is anti-symmetricwith respect to center line 716.

FIGS. 11A and 11B also show specific implementation of accessoryattachment feature 800 that can, for example, correspond to element 202shown in FIG. 6 and FIGS. 7A-7C. Magnetic assemblies 802 can include anumber of magnetic elements. The magnetic elements can be arranged insuch a way that the combined magnetic field matches the magnetic fieldof magnetic assembly 702.

Magnetic assembly 802 can include magnets 802 a, 802 b, and 802 c eachbeing about the same size as corresponding magnet 712 a, 712 b, and 712c in magnetic assembly 702. However, in order to maximize net attractionforce F_(net) and drive the magnetic interaction between the magneticfields to a desired equilibrium, magnets 802 a, b, c are aligned basedupon second magnetic polarity pattern {P2, P1, P2}. Magnetic assembly802 can also include magnets 804 a, 804 b, and 804 c each being aboutthe same size as corresponding magnets 714 a, 714 b, and 714 c.Moreover, in keeping with the overall goal of the magnetic interactionbetween the magnetic fields to equilibrate at the desired configurationof the devices, magnets 804 a, b, c can be aligned according to firstmagnetic polarity pattern {P1, P2, P1}.

FIG. 11B shows device attachment feature 700 in the active state due tothe magnetic interaction between magnetic assemblies 702 and 802. Inparticular, since the arrangement of magnetic elements betweenattachment feature 700 and those in accessory attachment feature 800“match”, then the magnetic interaction between the magnetic fields cancause magnetic assemblies 702 to move from the inactive state (i.e.,x=0) to the active state (i.e., x=x₀).

FIG. 12 illustrates a sequence of relative shift positions for themagnetic structure of magnetic assembly 702 and the complementary magnetstructure of magnetic assembly 802. Magnetic assembly 702 is shown to beencoded with coded magnetic sequence {+2, −1, +1, −1, +1, −2}. Magneticassembly 802 is shown to be encoded with complementary coded magneticsequence {−2, +1, −1, +1, −1, +2}. For this example, the magnets canhave the same or substantially the same magnetic field strength (oramplitude), which for the sake of this example is provided a unit of 1(where A=Attract, R=Repel, A=−R, A=1, R=−1). In this example, magneticassemblies 702 and 802 are moved relative to each other one “1L” lengthat a time (note that the anti-symmetry about center line 716 of thecoded magnetic sequence allows that the results of a leftward shiftmirror the results of a rightward shill, therefore, only a rightwardshift is shown).

For each relative alignment, the number of magnets that repel plus thenumber of magnets that attract is calculated, where each alignment has atotal force in accordance with a magnetic force function based upon themagnetic field strengths of the magnets. In other words, the totalmagnetic force between the first and second magnet structures can bedetermined as the sum from left to right along the structure of theindividual forces, at each magnet position, of each magnet or magnetpair interacting with its directly opposite corresponding magnet in theopposite magnet structure. Where only one magnet exists, thecorresponding magnet is zero, and the force is zero. Where two magnetsexist, the force is R for equal poles or A for opposite poles for eachunit magnet.

The total magnetic force can be computed for each of the figures andshown with each figure along with the relative shift value. Accordingly,using a specific coded magnetic sequence {+2, −1, +1, −1, +1, −2} canresult in net magnetic attractive force F_(net) varying from −3 (i.e.,3R) to +8 (i.e., +8A) where the peak occurs when magnetic assemblies 702and 802 are aligned such that their respective codes are also aligned.It should be noted that the off peak net magnetic force can vary from −3to +4. As such, the net magnetic force can cause magnetic assemblies 702to generally repel each other unless they are aligned such that each oftheir magnets is correlated with a complementary magnet (i.e., amagnet's South pole aligns with another magnet's North pole, or viceversa). In other words, magnetic assemblies 702 and 802 highly correlatewhen they are aligned such that they substantially mirror each other.

It should also be noted that when magnetic assemblies 702 and 802 are180° out of phase (i.e., something akin to top to bottom mis-alignmentalso referred to as upside down) the net magnetic force generated can beon the order of 8R. Hence, it is highly unlikely that devices beingmagnetically attached to each other using magnetic assemblies 702 and802 can be attached upside down.

FIG. 13 illustrates graph 900 of function F_(NET)(L). FunctionF_(NET)(L) describes net magnetic force F_(NET) as a function of shiftdisplacement (L) shown in FIG. 12 for the coded magnet structures inmagnetic assembly 702 and magnetic assembly 802. It should be noted thatthe symmetric nature of the coded magnetic structures in magneticassemblies 702 and 802 about center line 716 provides that functionF_(NET)(L) is also anti-symmetric about center line 716. In this way,the results of FIG. 12 can be plotted on the right side of center line716 and reflected about center line 716 to populate the left side ofgraph 900.

As shown in FIG. 13, function F_(NET)(L) has a global maximum value whenmagnetic assemblies 702 and 802 correlate at a position corresponding tocenter line 716. In other words, function F_(NET) (L=0) reaches amaximum (i.e., 8A) when all magnetic elements in magnetic assemblies 702and 802 having opposite polarities align with each other. Any otherconfiguration (i.e., F_(NET)(L≠0) results in net magnetic force F_(NET)being less than the global maximum value (of 8A). It should further benoted, however, that function F_(NET)(L) has at least two local maximavalues (i.e., F_(NET)(L=±3)) that permits a weak attachment betweenmagnetic assemblies 702 and 802. However, a strong, durable attachmentcan only occur when device magnetic attachment feature 700 associatedwith magnetic assembly 702 is properly activated. Therefore, byestablishing activation force F_(ACT) satisfying Eq. (8), a “falseactivations” of device magnetic attachment feature 700 or a weakattachment between magnetic assemblies 702 and 802 can be avoided.

F _(NET)(L=local maxima)≦F _(ACT) ≦F _(NET)(L=global maximum)  Eq. (8).

It should also be noted that activation force F_(ACT) is related toretaining force F_(retain) through Eq. (6). In this way, Eq. (6) and Eq.(8) in view of function F_(NET)(L) can be can be used to determine asuitable value for spring constant k.

FIGS. 14 and 15 show other embodiments where magnetic elements can bearranged vertically and horizontally. In addition, the magnetic elementscan be sized to have polarities that also extend both horizontally andvertically. For example, arrangement 1000 shows two rows of magneticelements where each magnetic element extends height H in the verticaldirection. In the arrangement shown, each vertically arranged magneticelement has the same magnetic polarity forming equivalent magneticstructure 1002. In other words, both arrangement 1000 and arrangement1002 can be both be characterized as having the coded magnetic sequence{+2, −2, +2, −2, +2, −2}.

FIG. 15 shows a top view of magnetic array configured as two dimensionalcoded magnetic sequence 1004 in accordance with the describedembodiments. Two dimensional coded magnetic sequence 1004 can be used toextend the combined magnetic field over an area that extends in both thex and y directions. This extended area can result in an overall increasein the area available to propagate magnetic field lines that can resultin an increase in magnetic flux and a commensurate increase in netmagnetic attractive force. In addition to providing an improved magneticattachment, two dimensional coded magnetic sequence 1004 can approximatenon-integer values of magnetic properties, such as magnetic strength.For example, with magnetic arrangement 1004, the magnetic fields of thevarious components can combine to approximate the coded magneticsequence {+1.5, −1.5, +1.5, −1.5, +1.5, −1.5}. Furthermore, twodimensional coded magnetic sequence 1004 can assist in providing avertical alignment in addition to a horizontal alignment.

For the remainder of this discussion, various embodiments of accessorydevice 200 are discussed.

In one embodiment, accessory device 200 can include a number ofprotective elements that can be used to protect certain aspects ofelectronic device 100. For example, accessory device 200 can take theform of a protective cover. The protective cover can include a flappivotally connected to a hinge assembly. The hinge assembly can, inturn, be coupled to electronic device 100 by way of accessory attachmentfeature 202. In this way, the flap portion can be used as a protectivecover to protect aspects of electronic device 100 such as a display. Theflap can be formed of various materials such as plastic, cloth, and soforth. The flap can be segmented in such a way that a segment of theflap can be lifted to expose a corresponding portion of the display. Theflap can also include a functional element that can cooperate with acorresponding functional element in electronic device 100. In this way,manipulating the flap can result in an alteration in the operation ofelectronic device 100.

The flap can include magnetic material that can be used to activate amagnetically sensitive circuit in electronic device 100 based upon, forexample, the Hall Effect. The magnetically sensitive circuit can respondby generating a signal that can, in turn, be used to alter an operatingstate of electronic device 100. Since the cover can be easily attacheddirectly to the housing of the tablet device without fasteners, thecover can essentially conform to the shape of electronic device 100. Inthis way, the cover will not detract or otherwise obscure the look andfeel of electronic device 100.

In one embodiment, accessory device 200 can be used to enhance theoverall functionality of electronic device 100. For example, accessorydevice 200 can be configured to act as a hanging apparatus. Whenmagnetically attached to electronic device 100, accessory device 200 canbe used to hang electronic device 100. In this way, electronic device100 can be used as a display for presenting visual content such as art,movies, photos and so forth on a wall or suspended from a ceiling. As ahanging apparatus, accessory device 200 can be used to hang electronicdevice 100 from a wall or a ceiling. Electronic device 100 can be easilyremoved by simply exerting a releasing force sufficient to overcome thenet magnetic attractive force F_(NET). Accessory device 200 can be leftin place and be used to reattach electronic device 100 (or anotherdevice) at a later time.

In one embodiment, accessory device 200 can also take the form of aholding mechanism for attaching objects that are not by themselvesequipped to magnetically attach to electronic device 100. For example,accessory device 200 can be configured to carry a stylus or other suchinput device. The stylus can be used to provide inputs to the electronicdevice. In some cases, accessory device 200 can provide a signal toelectronic device 100 indicating the presence of the stylus. The signalcan cause electronic device 100 to enter into a stylus recognitionstate, for example. More particularly, when accessory device 200 ismagnetically attached to electronic device 100, electronic device 100can activate a stylus input state in order to recognize stylus typeinputs. When accessory device 200 is removed, electronic device 100 cande-activate the stylus input state. In this way, the stylus can beconveniently attached/detached to electronic device 100 when needed.

Accessory device 200 can take the form of a support that can be used toenhance the functionality of electronic device 100. For example,accessory device 200 can be configured to act as a display stand onwhich a display of electronic device 100 can be viewed at a comfortableviewing angle such as 75°. In other words, when placed upon a horizontalsurface such as a table or desk, accessory device 200 can supportelectronic device 100 in such a way that the visual content presented atthe display can be viewed at about a viewing angle of approximately 75°.

Accessory device 200 can also take the form of a support that can beused to enhance the functionality of electronic device 100 in a keyboardstate. In the keyboard state, accessory device 200 can be used topresent a touch pad surface at an angle that is ergonomically friendly.In this way, input touch events can be applied (to a virtual keyboard,for example) at an angle that does not overtax a user's wrist, hands,arms, etc.

The remainder of this discussion will describe particular embodiments ofdevices that can use the magnetic attachment system. In particular, FIG.16A and FIG. 16B show electronic device 100 presented in terms of tabletdevice 1100 and accessory device 200 is shown as cover assembly 1200each in perspective top views These elements may generally correspond toany of those previously mentioned. In particular, FIGS. 16A and 16Bshows two perspective views of tablet device 1100 and cover assembly1200 in the open configuration. For example, FIG. 16A shows deviceattachment feature 108 included in tablet device 1100 and itsrelationship to tablet device 1100. FIG. 16B, on the other hand, is theview presented in FIG. 16A rotated about 180° to provide a second viewof attachment feature 202 and its relationship with cover assembly 1200.

Tablet device 1100 can take the form of a tablet computing device suchas the iPad™ manufactured by Apple Inc. of Cupertino, Calif. Referringnow to FIG. 16A, tablet device 1100 can include housing 1102 that canenclose and support device attachment feature 108. In order to notinterfere with the magnetic field generated by device attachment feature108, at least that portion of housing 1102 nearest device attachmentfeature 108 can be formed of any number of non-magnetic materials suchas plastic or non-magnetic metal such as aluminum. Housing 1102 can alsoenclose and support internally various structural and electricalcomponents (including integrated circuit chips and other circuitry) toprovide computing operations for tablet device 1100. Housing 1102 caninclude opening 1104 for placing internal components and can be sized toaccommodate a display assembly or system suitable for providing a userwith at least visual content as for example via a display. In somecases, the display assembly can include touch sensitive capabilitiesproviding the user with the ability to provide tactile inputs to tabletdevice 1100 using touch inputs. The display assembly can be formed of anumber of layers including a topmost layer taking the form oftransparent cover glass 1106 formed of polycarbonate or otherappropriate plastic or highly polished glass. Using highly polishedglass, cover glass 1106 can take the form of cover glass 1106substantially filling opening 1104.

Although not shown, the display assembly underlying cover glass 1106 canbe used to display images using any suitable display technology, such asLCD, LED, OLED, electronic or e-inks, and so on. The display assemblycan be placed and secured within the cavity using a variety ofmechanisms. In one embodiment, the display assembly is snapped into thecavity. It can be placed flush with the adjacent portion of the housing.In this way, the display can present visual content that can includevisual, still images, as well as icons such as graphical user interface(GUI) that can provide information the user (e.g., text, objects,graphics) as well as receive user provided inputs. In some cases,displayed icons can be moved by a user to a more convenient location onthe display.

In some embodiments, a display mask can be applied to, or incorporatedwithin or under cover glass 1106. The display mask can be used to accentan unmasked portion of the display used to present visual content andcan be used to make less obvious device attachment feature 108 andsecuring attachment feature 110.

Tablet device 1100 can include various ports that can be used to passinformation between tablet device 1100 and the external environment. Inparticular, data port 1108 can facilitate the transfer of data and powerwhereas speakers 1110 can be used to output audio content. Home button1112 can be used to provide an input signal that can be used by aprocessor included in tablet device 1100. The processor can use thesignal from home button 1112 to alter the operating state of tabletdevice 1100. For example, home button 1112 can be used to reset acurrently active page presented by the display assembly.

In one embodiment, accessory device 200 can take the form cover assembly1200. Cover assembly 1200 can have a look and feel that complements thatof the tablet device 1100 adding to overall look and feel of tabletdevice 1100. Cover assembly 1200 is shown in FIGS. 16A and 16B attachedto tablet device 1100 in an open configuration in which cover glass 1106is fully viewable. Cover assembly 1200 can include flap 1202. In oneembodiment, flap 1202 can have a size and shape in accordance with coverglass 1106. Flap 1202 can be pivotally connected to accessory attachmentfeature 202 by way of a hinge assembly (not shown). The magneticattachment force between attachment feature 202 and device attachmentfeature 108 can maintain cover assembly 1200 and tablet device 1100 in aproper orientation and placement vis-a-vis flap 1202 and cover glass1106. By proper orientation it is meant that cover assembly 1200 canonly properly attach to tablet device 1100 having flap 1202 and coverglass 1106 aligned in a mating engagement. The mating arrangementbetween cover glass 1106 and flap 1202 is such that flap 1202 coverssubstantially all of cover glass 1106 when flap 1202 is placed incontact with cover glass 1106 as shown in FIG. 17A below.

FIGS. 17A and 17B show cover assembly 1200 and tablet device 1100magnetically attached to each other. FIG. 17A shows a closedconfiguration in which cover glass 1106 is fully covered by and incontact with flap 1202. Cover assembly 1200 can pivot about hingeassembly 1204 from the closed configuration of FIG. 17A to an openconfiguration of FIG. 17B. In the closed configuration, inner layer 1206of cover assembly 1200 can come in direct contact with cover glass 1106.In one embodiment, inner layer 1206 can be formed of material that canpassively clean cover glass 1106. The passive cleaning by inner layer1206 of cover glass 1106 can be accomplished by movements of thoseportions of inner layer 1206 in contact with cover glass 1106. In aparticular embodiment, inner layer 1206 can be formed of a microfibermaterial.

In order to transition from the closed to the open configuration,releasing force F_(release) can be applied to flap 1202. Releasing forceF_(release) can overcome the magnetic attractive force betweenattachment feature 216 in flap 1202 and attachment feature 110 in tabletdevice 1100. Hence, cover assembly 1200 can be secured to tablet device1100 until releasing force F_(release) is applied to flap 1202. In thisway, flap 1202 can be used to protect cover glass 1106. For example,cover assembly 1200 can be magnetically attached to tablet device 1100.Flap 1202 can then be placed upon and magnetically secured to coverglass 1106 by the magnetic interaction between magnetic attachmentfeatures 110 and 216. Flap 1202 can be detached from cover glass 1106 bythe application of releasing force F_(release) directly to flap 1202.Releasing force F_(release) can overcome the magnetic attraction betweenmagnetic attachment features 110 and 216. Hence, flap 1202 can then moveaway from cover glass 1106 unhindered.

In order to maintain a good magnetic attachment between flap 1202 andmagnetic attachment feature 110, flap 1202 can include a number ofmagnetic elements. Some of the magnetic elements in flap 1202 caninteract with corresponding magnetic elements in magnetic attachmentfeature 110. The net magnetic attractive force generated between themagnetic elements can be strong enough to prevent inadvertent release offlap 1202 from cover glass 1106 during normal handling. The net magneticattractive force, however, can be overcome by releasing forceF_(release).

FIG. 18 shows a top view of a specific embodiment of cover assembly 1200in the form of segmented cover assembly 1300. Segmented cover assembly1300 can include body 1302. Body 1302 can have a size and shape inaccordance with cover glass 1106 of tablet 1100. Body 1302 can be formedfrom a single piece of foldable or pliable material. Body 1302 can alsobe divided into segments separated from each other by a folding region.In this way, the segments can be folded with respect to each other atthe folding regions. In one embodiment, body 1302 can be formed layersof material attached to one another forming a laminate structure. Eachlayer can take the form of a single piece of material that can have asize and shape in conformance with body 1302. Each layer can also have asize and shape that correspond to only a portion of body 1302. Forexample, a layer of rigid or semi-rigid material about the same size andshape of a segment can be attached to or otherwise associated with thesegment. In another example, a layer of rigid or semi-rigid materialhaving a size and shape in accordance with body 1302 can be used toprovide segmented cover assembly 1300 as a whole with a resilientfoundation. It should be noted that the layers can each be formed ofmaterials having desired properties. For example, a layer of segmentedcover assembly 1300 that conies in contact with delicate surfaces suchas glass can be formed of a soft material that will mar or otherwisedamage the delicate surface. In another embodiment, a material such asmicro-fiber can be used that can passively clean the delicate surface.On the other hand, a layer that is exposed to the external environmentcan be formed of a more rugged and durable material such as plastic orleather.

In a specific embodiment, segmented body 1302 can be partitioned into anumber of segments 1304-1310 interspersed with thinner, foldableportions 1312. Each of the segments 1304-1310 can include one or moreinserts disposed therein. By way of example, the segments can include apocket region where the inserts are placed or alternatively the insertsmay be embedded within the segments (e.g., insert molding). If pocketsused, the pocket region can have a size and shape to accommodatecorresponding inserts. The inserts can have various shapes but are mosttypically shaped to conform to the overall look of segmented body 1302(e.g., rectangular). The inserts can be used to provide structuralsupport for segmented body 1302. That is, the inserts can providestiffness to the cover assembly. In some cases, the inserts may bereferred to as stiffeners. As such, the cover assembly is relativelystiff except along the foldable regions that are thinner and do notinclude the inserts (e.g., allows folding) making segmented coverassembly 1300 more robust and easier to handle. In one embodimentsegments 1304, 1306, and 1310 can be related to segment 1308 in size inthe proportion of about 0.72 to 1 meaning that segments 1304, 1306 and1310 are sized in width to be about 72% of the width of segment 1308. Inthis way, a triangle having a appropriate angles can be formed (i.e.,about 75° for display stand and about 11° for keyboard stand discussedbelow).

Segments 1306, 1308, and 1310 can include inserts 1314, 1316, and 1318,respectively (shown in dotted lines form). Inserts 1314-1318 can beformed of rigid or semi-rigid material adding resiliency to body 1302.Examples of materials that can be used include plastics, fiber glass,carbon fiber composites, metals, and the like. Segment 1304 can includeinsert 1320 also formed of resilient material such as plastic but alsoarranged to accommodate magnetic elements 1322 some of which caninteract with magnetic elements in table device 1100 and morespecifically attachment feature 110.

Due to the ability of segmented body 1302 to fold and more particularlythe various segments to fold with respect to each other, most ofmagnetic elements 1322 can be used to magnetically interact withmagnetically active insert 1324 embedded in insert 1318. By magneticallybinding both active insert 1324 and magnetic elements 1322 varioussupport structures can be formed some of which can be triangular inshape. The triangular support structures can aid in the use of tabletdevice 1100. For example, one triangular support structure can be usedto support tablet device 1100 in such a way that visual content can bepresented at a desirable viewing angle of about 75° from horizontal.However, in order be able to appropriately fold segmented cover 1300,segment 1308 can be sized to be somewhat larger than segments 1304, 1306and 1310 (which are generally the same size). In this way, the segmentscan form a triangle having two equal sides and a longer third side, thetriangle having an interior angle of about 75°.

One approach to forming at least one triangular support structure caninclude segment 1304 folding with respect to segments 1306-1310 in sucha way that most of magnetic elements 1322 embedded in insert 1320magnetically attract the magnetically active insert 1324. In this way,segment 1304 and segment 1310 can be magnetically bound together forminga triangular support structure having the appropriate dimensions. Thetriangular support structure can be used as a stand onto which tabletdevice 1100 can be placed such that visual content can be displayed atabout 75°. In another example, segmented cover 1300 can be folded toform a triangular support structure that can be used as a keyboardsupport. Segmented cover 1300 can also be folded to form a triangularsupport structure that can be used to hang tablet device 1100 from ahorizontal support piece (such as a ceiling) or a vertical support piece(such as a wall).

Cover assembly 1300 can pivotally attach to accessory attachment feature202 by way of a hinge assembly. The hinge assembly can provide one ormore pivots to allow the cover to fold over on the device while thecover assembly is attached to the device through the magnets. In theillustrated embodiment, the hinge assembly can include first hingeportion (also referred to as first end lug) 1328 and a second hingeportion (or second end lug) 1330 disposed opposite the first end lug.First end lug 1328 can be rigidly connected to second end lug 1330 byway of connecting rod 1332 (shown in dotted line form) incorporated intoa tube portion of segmented body 1302. The longitudinal axis ofconnecting rod 1332 can act as pivot line 1333 about which the segmentedbody can pivot relative to the hinge assembly. Connecting rod 1332 canbe formed of metal or plastic strong enough to rigidly support coverassembly 1300 as well as any objects, such as tablet device 1100,magnetically attached to magnetic attachment feature 202.

In order to prevent metal on metal contact, first end lug 1328 andsecond end lug 1330 can each have protective layers 1336 and 1338,respectively, attached thereto. Protective layers (also referred to asbumpers) 1336 and 1338 can prevent direct contact between first end lug1328 and second end lug 1330 with housing 1102. This is particularlyimportant when end lugs 1328, 1330 and housing 1102 are formed of metal.The presence of bumpers 1336 and 1338 can prevent metal to metal contactbetween the end lugs and housing 1102 thereby eliminating the chance ofsubstantial wear and tear at the point of contact that can degrade theoverall look and feel of tablet device 1100.

In order to maintain their protective qualities, bumpers 1336 and 1338can be formed of material that is resilient, durable, and resistsmarring the finish of the exterior surface of tablet device 1102. Thisis particularly important due to the tight tolerances required for goodmagnetic attachment and the number of attachment cycles expected duringthe operational life of tablet device 1100. Accordingly, bumpers 1336and 1338 can be formed of soft plastic, cloth or paper that can beattached to the end lugs using any suitable adhesive. It should also benoted that in some cases, the bumpers can be removed and replaced withfresh bumpers when needed.

First end lug 1328 and second end lug 1330 can be magnetically connectedto the electronic device by way of hinge span 1340 that is configured topivot with respect to the end lugs. The pivoting can be accomplishedusing hinge posts 1342 (a portion of which can be exposed). Hinge posts1342 can rotatably secure hinge span 1340 to both first end lug 1328 andsecond end lug 1330. Hinge span 1304 can include magnetic elements. Themagnetic elements can be arranged to magnetically attach hinge span 1340to a magnetic attachment feature having a matching arrangement ofmagnetic elements in the electronic device. In order to fix the magneticelements in place within hinge span 1340, hinge posts 1342 can be usedto secure magnetic elements located at both ends of hinge span 1340reducing the likelihood that the magnetic elements in hinge span 1340will move about having the potential for disrupting the magneticattachment between hinge span 1340 and the magnetic attachment featurein the electronic device.

In order to assure that there is no interference between the magneticelements in hinge span 1340 and the corresponding magnetic elements inthe electronic device, hinge span 1340 can be formed of magneticallyinactive material such as plastic or non-magnetic metal such asaluminum. When hinge span 1340 is formed of magnetically inactive metal,such as aluminum, metal to metal contact between hinge span 1340 andhousing 1102 of electronic device 1100 can be prevented with the use ofprotective layer 1344. Protective layer 1344 can be applied to thesurface of hinge span 1340 that faces housing 1102 when hinge span 1340and electronic device 1100 are magnetically attached to each other.Protective layer 1344 (also referred to as label 1344) can be formed ofmany materials that will not mar the finish of housing 1102. Suchmaterials can include, for example, paper, cloth, plastic, and so forth.

FIGS. 19A and 19B show a more detailed view of two embodiments of hingespan 1340. More specifically, FIG. 19A shows embodiment 1400 of thehinge span where magnetically inert spacers are used to separate and fixthe magnetic elements. In particular, hinge span 1400 can enclose andsupport magnetic elements 1402 used by magnetic attachment feature 202to magnetically attach segmented cover assembly 1300 to tablet device1100. Magnetic elements 1402 can be arranged in a specific configurationthat matches corresponding magnetic elements in device attachmentfeature 108 in tablet device 1100. In this way, segmented cover assembly1300 and tablet device 1100 can precisely and repeatedly attach to eachother.

In order to maintain repeatable and stable magnetic engagement over anextended period of time, magnetic elements 1402 can remain in a stableconfiguration. In other words, magnetic elements 1402 in hinge span 1400should remain in their relative positions and polarities vis-à-vis thecorresponding magnetic elements in the magnetic attachment system intablet 1100 for an extended period of time. This is particularlyimportant when repeated attachment cycles are anticipated to occur overan expected operating life of cover assembly 1300 and/or tablet device1100.

Hence, to assure the integrity of the magnetic engagement over thecourse of many attachment cycles, the configuration of magnetic elements1402 can remain essentially fixed with respect to each other and to thecorresponding magnetic elements in device attachment feature 108. Hence,in order to assure that the physical layout of magnetic elements 1402remain essentially fixed, filler material 1404 can be inserted betweenthe various magnetic elements in hinge span 1400. Filler material 1404can be non-magnetic material such as plastic. Filler material 1404 canbe shaped to tightly fit in the interstitial spaces between the magneticelements. In this way, magnetic elements 1402 remain in a fixed andstable configuration for an extended period of time.

In the other hand. FIG. 19B shows another embodiment of hinge span 1340in the form of hinge span 1410 that utilizes the mutual magneticattraction between physically adjacent magnetic elements for fixing themagnetic elements in place. In this way, the number of component partsis reduced. Furthermore, due to the reduced area taken up by magneticelements 1402, the corresponding magnetic flux density can increased.However, end plugs 1412 can be used to fix those magnetic elementslocated at either end of hinge span 1410 End plugs 1412 can be necessaryto overcome a net magnetic repulsive force when the magnetic elements ateither end of hinge span 1410 have aligned polarities. In addition toend plugs 1412, an alternative embodiment can provide for centrallylocated spacer 1414. Centrally located spacer 1414 can be formed ofmagnetically inert material and be used to fix magnetic elements 1402 inplace.

FIG. 19C shows that portion of hinge span 1340 that forms part of theengagement surface when segmented cover assembly 1300 is magneticallyattached to tablet device 1100. In particular, label 1344 is shownattached to hinge span 1340 using adhesive such as glue. It should benoted, that label 1344 is arranged to conform to the shape of thatportion of housing 1102 that also forms part of the engagement surface.In this way, the separation distance between corresponding magneticelements can be minimized.

FIG. 20A shows a representative side view of segmented cover assembly1300 magnetically attached to tablet device 1100. FIG. 20B showrepresentative cross sectional views of segmented cover assembly1300/tablet device 1100 along line AA shown in FIG. 18. FIG. 20B shows acovered configuration and FIG. 20C shows a folded back configurationthat fully exposes protective layer 1106 of tablet device 1100.

FIG. 21A shows a cross sectional side view 1500 of hinge span 1340magnetically attached to housing 1102 having a curved shape. In thisembodiment, housing 1102 can have a curved shape and is formed ofnon-magnetic material such as aluminum. Magnetic element 1502 can beincorporated into device attachment feature 108 in tablet device 1102.In some embodiments, in order to prevent metal to metal contact, inthose embodiments in which magnetic element 1502 is metal, a protectivefilm can be attached to an engagement surface of magnetic element 1502that prevents magnetic element 1502 from contacting housing 1102directly. The protective film can be thin enough to be neglected whenconsidering the magnetic engagement force between corresponding magneticelements. The protective film can be unnecessary if magnetic element1502 is not formed of metal or if that portion of housing 1102 thatcontacts magnetic element 1502 is not metal.

Magnetic element 1502 can magnetically interact with correspondingmagnetic element 1504 in hinge span 1340. Magnetic element 1504 can havethickness of about 2 mm. The magnetic interaction can create netmagnetic attractive force F_(NET) satisfying Eq. (3a) in whichseparation distance x_(scp) is about equal to the total of the thicknesst of housing 1102 and thickness “/” of label 1344. Thickness “/” can beon the order of about 0.2 mm. Therefore in order to minimize separationdistance x_(scp) (and thereby increase F_(NET)), magnetic element 1502can be shaped to conform to interior surface 1506 of housing 1102.Furthermore, label 1344 and magnetic element 1504 can each be shaped toconform to exterior surface 1508 of housing 1102. In this way, thedistance between magnetic element 1502 and magnetic element 1504 can bereduced to about the thickness t of housing 1102 and thickness / oflabel 1344.

In order to further improve net attractive magnetic force F_(NET)between magnetic elements 1502 and 1504, magnetic shunt 1510 can beglued to and enclose that portion of magnetic element 1504 facing awayfrom housing 1102. Magnetic shunt 1510 can be formed of magneticallyactive material such as steel or iron. The magnetically active materialcan redirect magnetic flux lines that would otherwise be directed awayfrom magnetic element 1502 towards housing 1102 thereby increasing thetotal magnetic flux density B_(TOTAL) between magnetic element 1502 andmagnetic element 1504 resulting in a commensurate increase in netmagnetic attractive force F_(NET). Magnetic shunt 1510 can, in turn, beglued to housing 1512 of hinge span 1340. It should be noted, that inorder to assure that only label 1344 contacts exterior surface 1508 ofhousing 1102 (to avoid metal to metal contact), label 1344 is proud(i.e., protrudes) of housing 1512 of hinge span 1340 by about distance“d”. Nominally, distance d can be on the order of about 0.1 mm.

Since net magnetic force F_(NET) depends in part on separation distancebetween cooperating magnetic elements, the overall integrity of themagnetic attachment between the magnetic attachment system in tabletdevice 1100 and the magnetic elements in hinge span 1340 can be affectedby the actual separation distance between cooperating magnetic elementsas well as the consistency of the separation distance along length L ofhinge span 1340. In order to provide a highly correlated magneticattractive force along hinge span 1340, the separation distances betweenthe magnetic elements in hinge span 1340 and those of the magneticattachment system in tablet device 1100 are well controlled.

FIG. 21B shows cross sectional view 1550 of hinge span 1340 magneticallyattached to housing 1102 having a flat surface. In this arrangement,label 1344 and magnet 1554 can each conform to the flat shape of housing1102.

In order to assure consistency of the net magnetic attractive forcealong length L of hinge span 1340, the components of hinge span 1340 canbe assembled using fixture 1600 shown in cross section in FIG. 22A andin perspective view in FIG. 22B. Fixture 1600 can have surface 1602 thatconforms to the shape of the exterior surface of housing 1102. In orderto assemble hinge span 1340 in a manner that assures consistent magneticattractive force along the length L of hinge span 1340 (as well as toprovide an aesthetically pleasing look), label 1344 can be temporarilyattached to surface 1602 of fixture 1600. Since surface 1602substantially conforms to the shape of exterior surface 1508, label 1344will have a shape that also conforms to the shape of exterior surface1508. In one embodiment, a partial vacuum can be created within fixture1600 that causes label 1344 to attach to surface 1602 under suction. Inthis way, the assembled hinge span can be detached from surface 1602 bysimply removing the partial vacuum.

Once label 1344 is secured to surface 1602 of fixture 1600, magneticelement 1504 can be placed in direct contact with and attached to label1344 using any appropriate adhesive. In order to reduce separationdistance as much as possible, magnetic element 1504 can have a shapethat conforms to that of both labels 1344 and surface 1602. In this way,the conformal shaping of both label 1344 and magnetic element 1504assures a minimum separation distance between magnetic element 1506 and1502. Magnetic element 1504 can then be glued to magnetic shunt 1510formed of magnetically active materials such as steel to focus magneticflux towards magnetic element 1502. Metal shunt 1510 can then beenclosed by and glued to hinge span housing 1512 leaving about d=0.1 mmof label 1344 protruding from housing 1512.

In addition to providing protection to tablet device 1100, segmentedcover assembly 1300 can be manipulated to form useful supportstructures. Accordingly, FIGS. 23 through 26 show useful arrangements ofcover assembly 1300 in accordance with the described embodiments.

For example, as shown in FIG. 23, segmented cover assembly 1300 can befolded such that the magnetically active portion of insert 1324magnetically interacts with magnetic elements 1322. It should be notedthat the magnetic force used to maintain triangular support structure1700 is about in the range of 5-10 newtons (NT). In this way, triangularsupport structure 1700 can be prevented from unwrapping inadvertently.Triangular support structure 1700 can be formed that can be used in manyways to augment tablet device 1100. For example, triangular supportstructure 1700 can be used to support tablet device 1100 in such a waythat touch sensitive surface 1702 is positioned relative to a supportsurface at an ergonomically advantageous angle. In this way, using touchsensitive surface 1702 can be a user friendly experience. This isparticularly relevant in those situations where the touch sensitivesurface is used over an extended period of time. For example, a virtualkeyboard can be presented at touch sensitive surface 1702. The virtualkeyboard can be used to input data to tablet device 1100. By usingtriangular support structure 1700 to support tablet device 1100 at theergonomically friendly angle, the deleterious effects of repetitivemovements can be reduced or even eliminated.

FIGS. 24A and 24B show another folded implementation of segmented coverassembly 1300 in which triangular support structure 1700 can be used tosupport tablet device 1100 in a viewing state. By viewing state it ismeant that visual content (visual, stills, animation, etc.) can bepresented at a viewer friendly angle of about 75° from horizontal. Inthis “kickstand” state, visual content can be presented for easyviewing. A viewable area of tablet device 1100 can be presented at anangle of about 75° which has been found to be within a range of viewingangles considered optimal for a good viewing experience.

FIGS. 25A-25B show segmented cover assembly 1300 folded into varioushanging embodiments. By hanging embodiments, it is meant that by foldingsegmented cover assembly 1300 into an appropriate triangular shape,tablet device 1100 can be suspended from above as shown in FIG. 26A inthe form of hanger 1900. Hanger 1900 can be used to suspend tabletdevice 1100 from above. For example, hanger 1900 can be suspendeddirectly from a ceiling using a support piece such as a rod. Hanger 1900can be created simply by folding segmented cover assembly 1300 in afirst direction until embedded magnets 1322 magnetically engagemagnetically active insert 1324 that can be formed of steel or iron. Themagnetic circuit formed by the engagement of embedded magnets 1322 andmagnetically active insert 1324 can provide sufficient support forsafely suspending tablet device 1100 from any horizontally alignedsupport structure.

FIG. 25B shows hanger embodiments suitable for hanging tablet device1100 from a vertically aligned support structure such as a wall. Inparticular, hanger 1910 can be mechanically attached to a wall or othervertical support structure. Hanger 1910 can then be used to suspendtablet device 1100 along the lines of a wall mount. In this way, tabletdevice 1100 can be used to present visual content along the lines of avisual display for visual content, or wall hanging for still images suchas photos, art, and the like.

FIGS. 26A-26B show shows arrangement 2000 where triangular supportstructure 1700 can be used as a handle. Again by folding segmented coverassembly 1300 such that segmented portions interact with each other toform triangular support structure that can be used as a handle. As such,tablet device 1100 can be picked up as one would pick up a book forviewing. The body of segmented cover assembly 1300 can provideconvenient grasping features that can be used to more firmly grasptriangular support structure 1700 when being used to hold tablet device1100 as a book.

In those cases where tablet device 1100 includes image capture devices,such as a front facing camera 2002 and rear facing camera 2004, visualcontent can be presented by tablet device 1100. In this way, triangularsupport structure 1700 can be used as a holder along the lines of acamera handle. As such, triangular support structure 1700 can provide aconvenient and effective mechanism for aiding in the image captureprocess. For example, when used to capture images, tablet device 1100can be firmly held by way of triangular support structure 1700 and rearfacing camera 2004 can be pointed at a subject. The image of the subjectcan then be presented by tablet device 1100 at the display shown in FIG.25B. In this way, both front facing camera 2002 and/or rear facingcamera 2204 can be used to capture still images or video such as in avideo chat or simply view a video presentation. As part of a video chat,a visual chat participant can easily carry on a video conversation whileusing triangular support structure 1700 to hold tablet device 1100.

FIGS. 27A-27C show configuration 2100 of cover assembly 1300 and tabletdevice 1100 illustrating what is referred to as a peek mode of operationof tablet device 1100. More particularly, when segment 1304 is liftedfrom glass cover 1106, sensors in tablet device 1100 can detect thatsegment 1304 and only that segment has been lifted from glass layer1106. Once detected, tablet device 1100 can activate only the exposedportion 2102 of the display. For example, tablet device 1100 can utilizea Hall Effect sensor to detect that segment 1304 has been lifted fromglass cover 1106. Additional sensors, such as optical sensors can thendetect if only segment 1304 has been lifted or if additional segmentshave been lifted.

As shown in FIG. 27B, when tablet device 1100 has determined that onlysegment 1304 has been lifted, then tablet device 1100 can changeoperating state to “peek” state in which only the exposed portion 2102of the display actively presents visual content in the form of icons2104. Hence, information in the form of visual content such as time ofday, notes, and so forth can be presented for viewing on only thatportion of display viewable. Once the sensors detect that segment 1304has been placed back on glass layer 1106, tablet 1100 can return to theprevious operational state such as a sleep state. Furthermore, inanother embodiment, when an icon arranged to respond to a touch isdisplayed, then that portion of a touch sensitive layer corresponding tothe visible portion of the display can also be activated.

Furthermore, as shown in FIG. 27C, when additional segments are liftedfrom cover glass 1106 to further expose second portion 2106 of coverglass 1106, second portion 2106 of the display can be activated. In thisway, in the “extended” peek mode, additional visual information, such asicons 2108, can be presented in the portions of the display activated.It should be noted that as segments are lifted from cover glass 1106,additional segments of the display can be activated. In this way, anextended peek mode can be provided.

Alternatively, the tablet device 1100 can respond to the signals fromthe Hall Effect sensor(s) by simply powering up the display when theflap is moved away from the display and power down (sleep) when thedisplay is covered by the flap. In one embodiment, a subset of magneticelements 1322 can be used in conjunction with corresponding magneticelements 402 in attachment feature 110 to secure cover assembly 1300 totablet device 1100 on cover glass 1106. Furthermore, at least magnet1326 can be used to activate magnetically sensitive circuit 404. Forexample, when segmented cover 1300 is placed upon tablet device 1100 atcover glass 1106, the magnetic field from magnet 1326 can be detected bymagnetically sensitive circuit 404 that can take the form of a HallEffect sensor. The detection of the magnetic field can cause Hall Effectsensor 118 to generate a signal that can result in a change in theoperating state of tablet device 1100.

For example, when Hall Effect sensor 118 detects that segmented cover1300 is in contact with cover glass 1106 indicating that the display isnot viewable, then the signal sent by Hall Effect sensor 118 can beinterpreted by a processor in tablet device 1100 to change the currentoperating state to sleep state. On the other hand, when segment 1304 islifted from cover glass 1106, Hall Effect sensor 118 can respond to theremoval of the magnetic field from magnetic 1326 by sending anothersignal to the processor. The processor can interpret this signal byagain altering the current operating state. The altering can includechanging the operating state from the sleep state to an active state. Inanother embodiment, the processor can interpret the signal sent by HallEffect sensor 118 in conjunction with other sensors by altering theoperating state of tablet device 1100 to a peek mode in which only thatportion of the display exposed by the lifting of segment 1304 isactivated and capable of displaying visual content and/or receiving (orsending) tactile inputs.

In some cases, when segment 1306 is lifted from cover glass 1106 at thesame time that Hall Effect sensor 118 indicates that segment 1304 isalso lifted, the presence of sensors in addition to Hall Effect sensor118 can cause the processor to enter into an extended peek mode in whichadditional display resources corresponding to the additional exposedportion of the display are also activated. For example, if tablet device1100 includes other sensors (such as optical sensors) that can detectthe presence of a particular segment, then signals from Hall Effectsensor 118 in combination with other sensor signals can provide anindication to the processor that a particular portion or portions of thedisplay assembly are currently viewable and can thus be enabled topresent visual content.

FIG. 28A shows cover assembly 2200 in accordance with a particularembodiment. Cover assembly 2200 can include segmented cover 2202attached to pivoting assembly 2204 shown in an exploded view. Pivotingassembly 2204 can include end lugs 2206 and 2208 pivotally connected toeach other by way of hinge span 2210 and connecting rod 2212 (which canbe enclosed within sleeve 2214 that can in turn be connected to orenclosed within segmented cover 2202 and not seen). In this way, atleast two pivot lines 2216 and 2218 can be provided for pivotally movingend lugs 2206 and 2208, hinge span 2210 and connecting rod 2212. Forexample, hinge span 2210 (and end lugs 2206 and 2208) can rotate aboutpivot line 2216 whereas connecting rod 2212 (and end lugs 2206 and 2208)can rotate about pivot line 2218. It should be noted that connecting rod2212 and hinge span 2210 can pivot independent of each other. Thepivoting can occur at the same time or at different times givingpivoting assembly 2204 at least four independent directions of axialrotation.

In order to prevent metal on metal contact when hinge span 2210 ismagnetically coupled to tablet 1100, label 2220 can be affixed to anexternal surface of hinge span 2210 and bumpers 2222 can be affixed toan external surface of end lugs 2206 and 2208. Label 2220 and bumper2222 can be formed of material that can undergo repeated contact withhousing 102 without marring or otherwise damaging the appearance ofhousing 102. Accordingly, label 2220 and bumpers 2222 can be formed ofpaper, cloth, plastic and adhered to hinge span 2210 and end lugs 2206and 2208 using an adhesive such as glue. In some cases, the adhesive canhave properties that allow for easy replacement of label 2220 and/orbumpers 2222 when needed.

FIG. 28B shows an assembled embodiment of pivoting assembly 2204 showingpivot line 2216 about which end lugs 2206, 2208 and connecting rod 2212(in sleeve 2214) can rotate in two axial directions (i.e. clockwise andcounter-clockwise). It should be noted that end lugs 2206, 2208 andhinge span 2210 can rotate in two axial directions (i.e., clockwise andcounter-clockwise) with respect to pivot line 2218. In this way, endlugs 2206 and 2208 can rotate about pivot line 2216 and pivot line 2218with a total of four axial directions.

FIG. 28C shows hinge span 2210 illustrating in more detail end pins 2224and 2226 that can be used to mount hinge span 2210 into end lug 2206 andend lug 2208, respectively. Although not viewable in this figure, endpins 2224 and 2226 can further be used in conjunction with internalplugs to secure end unit magnetic elements incorporated within hingespan 2210. This is particularly useful in those situations where thecoded magnetic sequence of the magnetic elements incorporated withinhinge span 2210 causes the end unit magnetic elements to magneticallyrepel an adjacent neighbor magnetic element.

FIG. 28D shows an exploded view of hinge span 2210 in accordance withthe described embodiments. Magnetic elements 2228 can be configured as acoded magnetic structure in which individual magnetic elements can bearranged in a specific pattern of magnetic polarity, strength, size andso forth. In the embodiment shown, those magnets next to each otherhaving anti-aligned polarity can rely upon their mutual magneticattraction to maintain their position with the coded magnetic structure.However, magnetic elements placed next to each other having alignedmagnetic polarity can require an external force to overcome the mutualmagnetic repulsive force in order to maintain their position within thecoded magnetic structure. For example, magnetic element 2228-1 and2228-2 can each be formed of two magnets having aligned magnetic poles.In this situation, each of the two magnets that form magnetic element2228-1 (and 2228-2), for example, will have magnetic poles that arealigned and therefore will generate a net magnetic repulsive forcebetween them. Therefore, an externally applied constraint can be appliedusing, for example, plugs 2232-1 and 2232-2, respectively. The magneticattractive force provided by magnets 2228-3 and 2228-4 (that areanti-aligned with respect to magnets 2228-1 and 2228-2, respectively)can help in stabilizing the coded magnetic structure enclosed withinhinge span 2210. Spacer 2234 formed of magnetically inert material canbe used to provide additional physical integrity to the coded magneticstructure formed by magnetic elements 2228.

In order to improve an overall net magnetic attractive force, magneticshunt 2236 formed of magnetically active material such as steel, can beadhesively attached to a back end of magnetic elements 2228. The backend placement of shunt 2236 can help to re-direct magnetic field linesthat would otherwise propagate away from the engagement surface betweenhinge span 2210 and housing 1102. By deflecting the magnetic field linesback towards the engagement surface, the magnetic flux density providedby magnetic elements 2228 at the engagement surface can be commensurablyincreased resulting in an increased net magnetic attractive forcebetween magnetic elements 2228 and the corresponding magnetic componentswithin housing 1102.

As discussed previously, label 2220 can be adhesively attached tomagnetic elements 2228 (and spacer 2234, if present) which can, in turn,be adhesively attached to magnetic shunt 2236. Magnetic shunt 2236 canbe adhesively attached to opening 2238 in hinge span 2210 leaving label2220 proud by about a distance “d” which can be on the order of about0.1-0.2 mm preventing metal to metal contact between hinge span 2210 andhousing 1102.

It should be noted that in the keyboard arrangement and displayarrangement, hinge span 2210 can experience a shearing force due to theplacement of tablet device 1100 on a supporting surface at an angle. Theshearing force can be resisted by the net magnetic attractive forcegenerated between hinge span 2210 and the device attachment featuretablet device 1100.

FIG. 29 shows an exploded view of segmented cover 2202. Bottom layer2250 can come in direct contact with a protected surface such as a coverglass for a display. Bottom layer 2250 can be formed of a material thatcan passively clean the protected surface. The material can be, forexample, a microfiber material. Bottom layer 2250 can be attached tostiffening layer 2252 formed of resilient material such as plastic.Stiffening layer 2252 can, in turn, be adhesively attached to inserts2254 to form a laminate structure including adhesive layer 2256,laminate material 2258 and insert 2254. Some of inserts 2254 canaccommodate embedded components. For example, insert 2254-1 canaccommodate magnets 2260 some of which can cooperate with correspondingattachment feature 110 embedded in tablet device 1100 for securingsegmented cover 2202 to tablet device 1100. At least one magnet 2260-1can be positioned and sized to interact with a magnetically sensitivecircuit (such as a Hall Effect sensor) incorporated within tablet device1100. It should be noted that whereas some of magnets 2260 arespecifically allocated to interact only with attachment feature 110,substantially all of magnets 2260 can magnetically interact withmagnetically active plate 2262 embedded in segment 2254-2 used to formvarious triangular support structures. In this way, a strong magneticforce can be generated providing a stable foundation for the triangularsupport structure.

An additional laminate structure can be formed of adhesive layer(s)2256, laminate material 2258 and top layer 2264. In some embodiments, anintervening layer of material can be provided having a knitted structurethat can aid in the attachment of top layer 2264. Top layer 2264 can beformed of many materials such as plastic, leather, and so forth inkeeping with the overall look and feel of tablet device 1100. In orderto provide additional structural support, top layer 2264 can have edgesreinforced by reinforcement bars 2266 that can be formed of plastic orother rigid or semi-rigid material.

FIG. 30 shows a partial cross sectional view of segmented cover 2200shown in FIG. 29 placed in position upon cover layer 1106 of tabletdevice 1100. Of particular note is the relative positioning of magnet2260-1 and Hall Effect sensor 118. In this way, when segmented cover2200 is placed upon cover layer 1106, the magnetic field from magnet2260-1 can interact with Hall Effect sensor 118 that can respond bygenerating a signal. The signal can, in turn, be processed in such a waythat the operating state of tablet device 1100 can change in accordancewith the presence of cover 2200. On the other hand, the removal of cover2200 can cause the operating state to revert to the previous operatingstate, or another operating state such as peek mode. It should be notedthat the magnetic field density between magnetic element 2260-1 and HallEffect sensor 118 can be on the order of about 500 gauss. However, inthose embodiments where cover 2202 is flipped over to the back ofhousing 1102, the magnetic flux density at Hall Effect sensor 118 can beon the order of about 5 Gauss.

FIG. 31A shows cross sectional view of hinge span 2210 in activeengagement with device attachment feature 2300 incorporated into tabletdevice 1100. In particular, magnetic attachment feature 2300 includes atleast magnetic element 2302 forming a magnetic circuit with magneticelement 2228 (which is part of the coded magnetic structure incorporatedinto hinge span 2210). Magnetic shunt 2304 can be used to re-directmagnetic field lines that propagate from magnetic element 2302 in adirection other than that of magnetic element 2228. In this way, themagnetic flux density at engagement surface 2306 can be commensurablyincreased thereby increasing net magnetic attractive force F_(net).Magnetic attachment feature 2300 can be incorporated into barrel 2308 inhousing 1102 sized to accommodate both magnetic element 2302 and shunt2304. In the described embodiment, barrel 2308 can provide support formagnetic element 2302 and shunt 2304. Barrel 2308 can also direct themotion of magnetic element 2302 and shunt 2304 when magnetic attachmentfeature 2300 transitions between the active state and the inactivestates.

In order to ensure that net attractive force F_(NET) is appliedsubstantially normal to engagement surface 2306, the magnetization ofmagnetic element 2228 and magnet element 2302 can be configured suchthat their respective magnetization vectors M substantially align. Bymagnetization it is meant that the magnets can be manufactured havingmagnetic domains that are substantially aligned in the same direction.By aligning the magnetization vectors M₁ and M₂ of magnetic element 2302and magnetic element 2228, respectively, net magnetic force F_(NET) canbe generated substantially normal to engagement surface 2306.

FIG. 31B shows magnetic attachment feature 2300 in an inactive state.When in the inactive state, magnetic attachment feature 2300 is locatedat least distance x₀ from exterior surface of housing 1102 in order tosatisfy Eq. (1). Therefore, barrel 2308 must be able to accommodate themovement of magnetic element 2302 and shunt 2304 from x=0 in theinactive state to about x=x₀ in the active state.

FIG. 32 shows a representation of an embodiment of device attachmentfeature 108 in the form of attachment feature 2400. In particular,attachment 2400 can include magnetic elements 2402/shunt 2404 inattached to leaf spring 2406. Leaf spring 2406 can be secured directlyto shunt 2404 by way of fasteners 2408 and end supports 2410 by way offasteners 2412. End supports 2410 can be attached to a support structuresuch as a housing to provide support for attachment feature 2400. In oneembodiment, alignment posts 2414 can be used during assembly to providealignment for both end supports 2410 and leaf spring 2406. FIG. 33 showsa close up view of the support structure 2410/leaf spring 2406interface.

FIG. 34 shows a flowchart detailing a process 2500 in accordance withthe described embodiments. The process can begin at 2502 by providing afirst coded magnetic attachment feature in an inactive state. At 2504,using a second magnetic attachment feature to activate the first codedfirst magnetic attachment feature. At 2506, causing a magnetic fieldfrom the activated first magnetic attachment feature to interact with amagnetic field from the second magnetic attachment feature. At 2508,generating a net magnetic attachment force in accordance with theinteraction of the magnetic fields. At 2510, magnetically binding thefirst and second magnetic attachment features in accordance with the netmagnetic attachment force.

FIG. 35 shows a flowchart detailing process 2600 in accordance with thedescribed embodiments. Process 2600 can begin at 2602 by providing acoded magnetic attachment feature in an inactive state. In the inactivestate, magnetic flux density at a pre-determined distance for magneticelements in the coded magnetic attachment feature is less than athreshold value. At 2604, an external magnetic field is received at thecoded magnetic attachment feature. At 2606, if it is determined that theexternal magnetic field corresponds to magnetic elements that correlatewith the magnetic elements in the coded magnetic attachment feature,then at 2608, the coded magnetic attachment feature is activated,otherwise, process 2600 ends.

FIG. 36 shows a flowchart detailing process 2700 in accordance with thedescribed embodiments. Process 2700 can begin at 2702 by placing anelectronic device having a first and an accessory having second codedmagnetic attachment features in proximity to each other. At 2704, if themagnetic elements in the first and second coded magnetic attachmentfeatures correlate with each other, then at 2706, the first codedmagnetic attachment feature is activated. When the first coded magneticattachment feature is activated, then a magnetic flux density of amagnetic field generated by the first coded magnetic attachment featureincreases to a value above a threshold. The magnetic field interactionbetween the magnetic elements in the first and second magneticattachment features cause the electronic device and accessory tomagnetically attach to each other at 2708.

FIG. 37 shows a flowchart detailing a peek mode process 2800 inaccordance with the described embodiments. Process 2800 can begin at2802 by determining if a first portion of a display is uncovered. Byuncovered it is meant that visual content presented at the first portioncan be viewed. When it is determined that the first portion of thedisplay is uncovered, then at 2804, only that portion of the displaythat is determined to be uncovered can present visual content. In otherwords, a set of icons or other visual content can be displayed in theuncovered portion of the display, where the remainder of the display canremain blank or off. Next at 2806, visual content is displayed by theactivated portion of the display. Next at 2808, a determination is madeif a second portion of the display is uncovered, the second portionbeing different than the first portion. When it is determined that thesecond portion of the display is uncovered, then a second portion of thedisplay is activated at 2810. Visual content is then displayed at thesecond activated portion at 2812.

FIG. 38 shows a flowchart detailing process 2900 for forming a magneticstack incorporated into hinge span 1340 in accordance with the describedembodiments. Process 2900 for forming the magnetic stack incorporatedinto hinge span 1340 can begin at 2902 by providing a fixture. Thefixture having a shape, in accordance with an exterior shape of thehousing that defines the electronic device upon which the hinge spanwill magnetically attach. The fixture can also be connected to a vacuumsource that can be used to subsequently secure a protective film at2904. The protective film can be used to provide protection againstmetal to metal contact between the hinge span and the housing of theelectronic device. The protective film (also referred to as a label) canbe formed of resilient material and have a length consistent with thatof the hinge span. Once the label has been secured to the fixture usingthe vacuum, the label conforms to the contour of the fixture, and thusthe shape of the housing of the electronic device.

At 2906, a magnet is attached to the label at a first surface shaped toconform to the fixture (and the housing). In one embodiment, the labeland magnet can be glued to each other using adhesive. In anotherembodiment, the label can have an adhesive inner layer impregnated withglue that can attach the label to the magnet upon curing. At 2908, amagnetic shunt is glued to the magnet and label assembly. The magneticshunt can be formed of magnetically active material such as steel. Themagnetic shunt can interact with those magnetic field lines from themagnet initially directed away from the engagement surface between thehousing and the hinge span. The magnetic shunt can interact with themagnetic field lines by re-directing at least some of the magnetic fieldlines in a direction towards the magnet and the engagement surface. There-directed magnetic field lines can increase the magnetic flux densityat the engagement surface thereby increasing the net attractive magneticforce between magnetic elements in the electronic device and the hingespan.

At 2910, a hinge span enclosure can be glued to the magnetic shunt. Thehinge span enclosure can be used to support and protect the magneticelements used to magnetically attach the hinge span to the electronicdevice. It should be noted that the after the attachment of the hingespan enclosure, the label is proud of the hinge span enclosure by whichit is meant that the label protrudes a distance “d” from the hinge spanenclosure. In this way, there is no contact between the metal hinge spanenclosure and the metal housing of the electronic device.

FIG. 39 shows a flowchart detailing process 3000 for determining aconfiguration of magnetic elements in a magnetic stack used in amagnetic attachment system in accordance with the described embodiments.Process 3000 begins at 3002 by providing a first plurality of magneticelements in accordance with a first configuration. At 3004, a secondplurality of magnetic elements in accordance with a second configurationis provided. By first and second configuration, what is meant is thatthe first and second plurality of magnetic elements can be arranged inany manner deemed appropriate. For example, the first and secondconfiguration can relate to a physical size, a magnetic polarity, amagnetic strength, a relative position with respect to other magneticelements, and so on. Next, at 3006, a net magnetic force is created inone embodiment by positioning each of the first and second plurality ofmagnetic elements with respect to each other. In so doing, thosecorresponding magnetic elements having the same polarity will generate anegative (repulsive) magnetic force whereas those corresponding magneticelements having opposite polarities will generate a positive(attractive) magnetic force. At 3008, a total value of the net magneticforce for each of the corresponding one of the first and secondplurality of magnetic elements is determined. As mentioned above, sincesome magnetic elements can generate a negative magnetic force whereasothers a positive magnetic force for the same position, the total valueof the net magnetic force can be either positive, negative, or zero(indicating the positive and negative magnetic forces cancel each otherout to give no overall net magnetic force).

At 3010, a difference between a global maximum net total magnetic forceand first local maximum net total magnetic force is determined. Forexample, as shown in FIG. 13, the global maximum corresponds with atotal net magnetic force of about 8A (“A” being a unit magneticattractive force where “8A” is equivalent to “+8” where “+” indicatesattractive force). Moreover, a first local maximum net total value isabout 4A and a second local maximum net total value is about 1A. Inorder to avoid a “false activation” that can result in a weak magneticattraction, the difference between the global maximum net total magneticforce and the first local maximum net total magnetic force can indicatea probability that the magnetic attachment system will equilibrate atthe global maximum net total magnetic force (representing the strongestnet magnetic attraction) and the first local maximum net total magneticforce (representing a weak net magnetic attraction).

Therefore, if at 3012, the difference is acceptable (meaning that theglobal maximum is the likely equilibrium point), then process 3000stops, otherwise, the configuration of magnetic elements is changed at3014 and control is passed directly to 3006 for further evaluation.

FIG. 40 is a block diagram of an arrangement 3100 of functional modulesutilized by an electronic device. The electronic device can, forexample, be tablet device 1100. The arrangement 3100 includes anelectronic device 3102 that is able to output media for a user of theportable media device but also store and retrieve data with respect todata storage 3104. The arrangement 3100 also includes a graphical userinterface (GUI) manager 3106. The GUI manager 3106 operates to controlinformation being provided to and displayed on a display device. Thearrangement 3100 also includes a communication module 3108 thatfacilitates communication between the portable media device and anaccessory device. Still further, the arrangement 3100 includes anaccessory manager 3110 that operates to authenticate and acquire datafrom an accessory device that can be coupled to the portable mediadevice.

FIG. 41 is a block diagram of an electronic device 3150 suitable for usewith the described embodiments. The electronic device 3150 illustratescircuitry of a representative computing device. The electronic device3150 includes a processor 3152 that pertains to a microprocessor orcontroller for controlling the overall operation of the electronicdevice 3150. The electronic device 3150 stores media data pertaining tomedia items in a file system 3154 and a cache 3156. The file system 3154is, typically, a storage disk or a plurality of disks. The file system3154 typically provides high capacity storage capability for theelectronic device 3150. However, since the access time to the filesystem 3154 is relatively slow, the electronic device 3150 can alsoinclude a cache 3156. The cache 3156 is, for example, Random-AccessMemory (RAM) provided by semiconductor memory. The relative access timeto the cache 3156 is substantially shorter than for the file system3154. However, the cache 3156 does not have the large storage capacityof the file system 3154. Further, the file system 3154, when active,consumes more power than does the cache 3156. The power consumption isoften a concern when the electronic device 3150 is a portable mediadevice that is powered by a battery 3174. The electronic device 3150 canalso include a RAM 3170 and a Read-Only Memory (ROM) 3172. The ROM 3172can store programs, utilities or processes to be executed in anon-volatile manner. The RAM 3170 provides volatile data storage, suchas for the cache 3156.

The electronic device 3150 also includes a user input device 3158 thatallows a user of the electronic device 3150 to interact with theelectronic device 3150. For example, the user input device 3158 can takea variety of forms, such as a button, keypad, dial, touch screen, audioinput interface, visual/image capture input interface, input in the formof sensor data, etc. Still further, the electronic device 3150 includesa display 3160 (screen display) that can be controlled by the processor3152 to display information to the user. A data bus 3166 can facilitatedata transfer between at least the file system 3154, the cache 3156, theprocessor 3152, and the CODEC 3163.

In one embodiment, the electronic device 3150 serves to store aplurality of media items (e.g., songs, podcasts, etc.) in the filesystem 3154. When a user desires to have the electronic device play aparticular media item, a list of available media items is displayed onthe display 3160. Then, using the user input device 3158, a user canselect one of the available media items. The processor 3152, uponreceiving a selection of a particular media item, supplies the mediadata (e.g., audio file) for the particular media item to a coder/decoder(CODEC) 3163. The CODEC 3163 then produces analog output signals for aspeaker 3164. The speaker 3164 can be a speaker internal to theelectronic device 3150 or external to the electronic device 3150. Forexample, headphones or earphones that connect to the electronic device3150 would be considered an external speaker.

The electronic device 3150 also includes a network/bus interface 3161that couples to a data link 3162. The data link 3162 allows theelectronic device 3150 to couple to a host computer or to accessorydevices. The data link 3162 can be provided over a wired connection or awireless connection. In the case of a wireless connection, thenetwork/bus interface 3161 can include a wireless transceiver. The mediaitems (media assets) can pertain to one or more different types of mediacontent. In one embodiment, the media items are audio tracks (e.g.,songs, audio books, and podcasts). In another embodiment, the mediaitems are images (e.g., photos). However, in other embodiments, themedia items can be any combination of audio, graphical or visualcontent. Sensor 3176 can take the form of circuitry for detecting anynumber of stimuli. For example, sensor 3176 can include a Hall Effectsensor responsive to external magnetic field, an audio sensor, a lightsensor such as a photometer, and so on.

FIG. 39 is a block diagram of an arrangement 3000 of functional modulesutilized by an electronic device. The electronic device can, forexample, be tablet device 1100. The arrangement 3000 includes anelectronic device 3002 that is able to output media for a user of theportable media device but also store and retrieve data with respect todata storage 3004. The arrangement 3000 also includes a graphical userinterface (GUI) manager 3006. The GUI manager 3006 operates to controlinformation being provided to and displayed on a display device. Thearrangement 3000 also includes a communication module 3008 thatfacilitates communication between the portable media device and anaccessory device. Still further, the arrangement 3000 includes anaccessory manager 3010 that operates to authenticate and acquire datafrom an accessory device that can be coupled to the portable mediadevice.

FIG. 40 is a block diagram of an electronic device 3050 suitable for usewith the described embodiments. The electronic device 3050 illustratescircuitry of a representative computing device. The electronic device3050 includes a processor 3052 that pertains to a microprocessor orcontroller for controlling the overall operation of the electronicdevice 3050. The electronic device 3050 stores media data pertaining tomedia items in a file system 3054 and a cache 3056. The file system 3054is, typically, a storage disk or a plurality of disks. The file system3054 typically provides high capacity storage capability for theelectronic device 3050. However, since the access time to the filesystem 3054 is relatively slow, the electronic device 3050 can alsoinclude a cache 3056. The cache 3056 is, for example, Random-AccessMemory (RAM) provided by semiconductor memory. The relative access timeto the cache 3056 is substantially shorter than for the file system3054. However, the cache 3056 does not have the large storage capacityof the file system 3054. Further, the file system 3054, when active,consumes more power than does the cache 3056. The power consumption isoften a concern when the electronic device 3050 is a portable mediadevice that is powered by a batten 3074. The electronic device 3050 canalso include a RAM 3070 and a Read-Only Memory (ROM) 3072. The ROM 3072can store programs, utilities or processes to be executed in anon-volatile manner. The RAM 3070 provides volatile data storage, suchas for the cache 3056.

The electronic device 3050 also includes a user input device 3058 thatallows a user of the electronic device 3050 to interact with theelectronic device 3050. For example, the user input device 3058 can takea variety of forms, such as a button, keypad, dial, touch screen, audioinput interface, visual/image capture input interface, input in the formof sensor data, etc. Still further, the electronic device 3050 includesa display 3060 (screen display) that can be controlled by the processor3052 to display information to the user. A data bus 3066 can facilitatedata transfer between at least the file system 3054, the cache 3056, theprocessor 3052, and the CODEC 3063.

In one embodiment, the electronic device 3050 serves to store aplurality of media items (e.g., songs, podcasts, etc.) in the filesystem 3054. When a user desires to have the electronic device play aparticular media item, a list of available media items is displayed onthe display 3060. Then, using the user input device 3058, a user canselect one of the available media items. The processor 3052, uponreceiving a selection of a particular media item, supplies the mediadata (e.g., audio file) for the particular media item to a coder/decoder(CODEC) 3063. The CODEC 3063 then produces analog output signals for aspeaker 3064. The speaker 3064 can be a speaker internal to theelectronic device 3050 or external to the electronic device 3050. Forexample, headphones or earphones that connect to the electronic device3050 would be considered an external speaker.

The electronic device 3050 also includes a network/bus interface 3061that couples to a data link 3062. The data link 3062 allows theelectronic device 3050 to couple to a host computer or to accessorydevices. The data link 3062 can be provided over a wired connection or awireless connection. In the case of a wireless connection, thenetwork/bus interface 3061 can include a wireless transceiver. The mediaitems (media assets) can pertain to one or more different types of mediacontent. In one embodiment, the media items are audio tracks (e.g.,songs, audio books, and podcasts). In another embodiment, the mediaitems are images (e.g., photos). However, in other embodiments, themedia items can be any combination of audio, graphical or visualcontent. Sensor 3076 can take the form of circuitry for detecting anynumber of stimuli. For example, sensor 3076 can include a Hall Effectsensor responsive to external magnetic field, an audio sensor, a lightsensor such as a photometer, and so on.

The magnetic attachment feature can be used to magnetically attach atleast two objects. The objects can take many forms and perform manyfunctions. When magnetically attached to each other, the objects cancommunicate and interact with each other to form a cooperative system.The cooperating system can perform operations and provide functions thatcannot be provided by the separate objects individually. For example, atleast a first object and a second object can be magnetically attached toeach other such that the first object can be configured to provide asupport mechanism to the second object. The support mechanism can bemechanical in nature. For example, the first object can take the form ofa stand that can be used to support the second object on a workingsurface such as a table. In another example, the first object can takethe form of a hanging apparatus. As such, the first object can be usedto hang the second object that can then be used as a display forpresenting visual content such as a visual, still images like a picture,art work, and so on. The support mechanism can also be used as a handlefor conveniently grasping or holding the second object. This arrangementcan be particularly useful when the second object can present visualcontent such as images (still or visual), textual (as in an e-book) orhas image capture capabilities in which case the second object can beused as an image capture device such as a still or visual camera and thefirst object can be configured to act as a support such as a tripod orhandle.

The described embodiments can take many forms. For example, theattachment can occur between a first and second object where the firstobject and second object can take the form of electronic devices. Theelectronic devices can be magnetically attached to each other to form acooperative electronic system in which the electronic devices cancommunicate with each other. As part of this communication, informationcan be passed between the first and second electronic devices. Theinformation can be processed in whole or in part at either the first orsecond electronic device depending upon the nature of the processing. Inthis way, the cooperative electronic system can take advantage of thesynergistic effect of having multiple electronic devices magneticallyattached and in communication with each other. In one implementation,the communication can be carried out wirelessly using any suitablewireless communication protocol such as Bluetooth (BT), GSM, CDMA, WiFi,and so on.

The cooperative electronic system can take the form of an array ofelectronic devices. In one embodiment, the array of electronic devicescan act as a single unified display (along the lines of a mosaic). Inanother embodiment, the array of electronic devices can provide a singleor a set of functions (such as virtual keyboard). In still anotherembodiment, at least one of the electronic devices can take the form ofa power providing device that can be attached to the electronic deviceusing the magnetic attachment feature. The power providing device canutilize a mechanical connection such as a power port, or in some cases amagnetically based charging mechanism, to provide current to theelectronic device. The current can be used to charge a battery ifnecessary while providing power to operate the cooperative electronicsystem. The power provided can be passed from one device to another asin a bucket brigade to even out the power distribution and batterycharge levels in the cooperative electronic system.

The various aspects, embodiments, implementations or features of thedescribed embodiments can be used separately or in any combination.Various aspects of the described embodiments can be implemented bysoftware, hardware or a combination of hardware and software. Thedescribed embodiments can also be embodied as computer readable code ona non-transitory computer readable medium. The computer readable mediumis defined as any data storage device that can store data which canthereafter be read by a computer system. Examples of the computerreadable medium include read-only memory, random-access memory. CD-ROMs,DVDs, magnetic tape, and optical data storage devices. The computerreadable medium can also be distributed over network-coupled computersystems so that the computer readable code is stored and executed in adistributed fashion.

The foregoing description, for purposes of explanation, used specificnomenclature to provide a thorough understanding of the describedembodiments. However, it will be apparent to one skilled in the art thatthe specific details are not required in order to practice the describedembodiments. Thus, the foregoing descriptions of the specificembodiments described herein are presented for purposes of illustrationand description. They are not target to be exhaustive or to limit theembodiments to the precise forms disclosed. It will be apparent to oneof ordinary skill in the art that many modifications and variations arepossible in view of the above teachings.

The advantages of the embodiments described are numerous. Differentaspects, embodiments or implementations can yield one or more of thefollowing advantages. Many features and advantages of the presentembodiments are apparent from the written description and, thus, it isintended by the appended claims to cover all such features andadvantages of the invention. Further, since numerous modifications andchanges will readily occur to those skilled in the art, the embodimentsshould not be limited to the exact construction and operation asillustrated and described. Hence, all suitable modifications andequivalents can be resorted to as falling within the scope of theinvention.

What is claimed is:
 1. An accessory unit, comprising: an accessory body;and a magnetic assembly pivotally connected to the accessory body,comprising: a first plurality of magnetic elements arranged adjacent oneanother in a first relative size order along a first line and arrangedaccording to a first polarity pattern of alternating magneticpolarities, and a second plurality of magnetic elements arrangedadjacent to one another in a second relative size order along the firstline and according to a second polarity pattern of alternating magneticpolarities.
 2. The accessory unit as recited in claim 1, wherein themagnetic assembly is arranged to magnetically attach the accessory unitto a host unit, wherein the accessory body has a size and shape inaccordance with the host unit.
 3. The accessory unit as recited in claim1, wherein the first and second size orders and the first and secondpolarity patterns are complementary of each other.
 4. The accessory unitas recited in claim 3, wherein the first polarity pattern is {P1, P2,P1} and wherein the second polarity pattern is {P2, P1, P2}, wherein P1is a first polarity and P2 is an opposite polarity.
 5. The accessoryunit as recited in claim 3, wherein the first relative size order is{2L, 1L, 1L} and wherein the second relative size order is {1L, 1L, 2L},wherein 1L is an effective unit magnet length and 2L is about twice theeffective unit magnet length.
 6. The accessory unit as recited in claim5, wherein a 2L magnetic element comprises a configuration of a first 1Lmagnetic element having the first polarity P1 adjacent to a second 1Lmagnet having the first polarity P1, wherein the first 1L magnet and theadjacent second 1L magnet are held together against a mutual repulsivemagnetic force by an externally applied force.
 7. The accessory unit asrecited in claim 6, wherein the magnetic assembly further comprises ahousing having a front opening; and a magnetic shunt enclosed in thehousing and attached to a back portion of the first and second pluralityof magnetic elements, the magnetic shunt arranged to re-direct at leastsome magnetic field lines away from the back side of the housing andtowards the front opening thereby increasing a magnetic flux densitybetween the first and second plurality of magnetic elements and the hostunit.
 8. The accessory unit as recited in claim 7, further comprising: afirst end plug inserted into a first end of the magnetic shunt; and asecond end plug inserted into a second end of the magnetic shunt,wherein the first and second end plugs provide the externally appliedforce used to maintain the 2L magnetic element configuration, whereinadjacent magnetic elements having opposite magnet polarities are heldtogether by a mutually attractive magnetic force.
 9. The accessory unitas recited in claim 1, wherein the magnetic assembly further comprises:a first end lug pivotally connected to an end of the housing: a secondend lug pivotally connected to an opposite end of the housing, whereinthe first and second end lugs and the housing pivot about a first pivotline; a rigid connecting rod connecting the first and second end lugs; acollar sized to accommodate the rigid connecting rod, the collar andrigid connecting rod inserted into an opening in the accessory body, therigid connecting rod forming a second pivot line different than thefirst pivot line about which the first and second end lugs and housingpivot.
 10. A magnetic attachment method suitable for use with anaccessory unit, comprising: providing a magnetic assembly comprising afirst plurality of magnetic elements arranged adjacent one another in afirst relative size order along a first line and arranged according to afirst polarity pattern of alternating magnetic polarities and a secondplurality of magnetic elements arranged adjacent to one another in asecond relative size order along the first line and according to asecond polarity pattern of alternating magnetic polarities, wherein thefirst and second plurality of magnetic elements cooperate to form afirst magnetic sequence; placing the sequenced magnetic assembly inproximity to a host unit; causing the creation of a first magneticsurface by the host unit, the first magnetic surface being suitable formagnetic attachment; magnetically attaching the accessory unit and thehost unit at an engagement surface corresponding to the magneticsurface.
 11. The method as recited in claim 10, wherein the magneticassembly further comprises: a housing, the housing formed ofmagnetically inactive material; a magnetic shunt attached to a backportion of the first and second plurality of magnetic elements andfitted into a front side opening of the housing, the magnetic shuntarranged to re-direct at least some magnetic field lines from the firstand second magnetic elements that propagate towards the back side of thehousing towards the front side opening.
 12. The method as recited inclaim 10, wherein the first and second relative size orders and thefirst and second polarity patterns are complementary of each other. 13.The method as recited in claim 12, wherein the first polarity pattern is{P1, P2, P1} and wherein the second polarity pattern is {P2, P1, P2},wherein P1 is a first polarity and P2 is an opposite polarity.
 14. Themethod as recited in claim 13, wherein the first relative size order is{2L, 1L, 1L} and wherein the second relative size order is {1L, 1L, 2L},wherein 1L is an effective unit magnet length and 2L is about twice theeffective unit magnet length.
 15. The method as recited in claim 14,wherein a 2L magnetic element comprises a configuration of a first 1Lmagnetic element having the first polarity P1 adjacent to a second 1Lmagnet having the first polarity P1, wherein the first 1L magnet and theadjacent second 1L magnet are held together against a mutual repulsivemagnetic force by an externally applied force.
 16. An accessory unit,comprising: an accessory body having a first magnetic element; and asecond magnetic element pivotally connected to the accessory body,wherein the second magnetic element magnetically attaches the accessoryunit pivotally to a first portion of a host unit and wherein the firstmagnetic element cooperates with the second magnetic element tomagnetically attach the accessory body to a second portion of the hostunit, wherein the first and second magnetic elements are independent ofeach other.
 17. The accessory unit as recited in claim 16, wherein thesecond magnetic element comprises: a first plurality of magneticelements arranged adjacent one another in a first relative size orderalong a first line and arranged according to a first polarity pattern ofalternating magnetic polarities; and a second plurality of magneticelements arranged adjacent to one another in a second relative sizeorder along the first line and according to a second polarity pattern ofalternating magnetic polarities.
 18. The accessory unit as recited inclaim 17, wherein the second magnetic element causes the host unit tocreate a first magnetic surface, the first magnetic surface beingsuitable for magnetically attaching the second magnetic element to thehost unit.
 19. The accessory unit as recited in claim 17, wherein theaccessory body has a size and shape in accordance with the host unit.20. The accessory unit as recited in claim 19, wherein the first magnetis a third plurality of magnetic elements.
 21. The accessory unit asrecited in claim 20, wherein the third plurality of magnetic elements isarranged in alternating polarity.
 22. The accessory unit as recited inclaim 21, wherein not all of the third plurality of magnetic elementsare used to magnetically attach the accessory body to the second portionof the host unit.
 23. The accessory unit as recited in claim 22, whereinthe at least one magnetic element not used to magnetically attach theaccessory body to the second portion of the host is detected by amagnetically sensitive circuit in the host unit when the accessory bodymagnetically attached to the host unit.
 24. The accessory unit asrecited in claim 23, wherein the magnetically sensitive circuit is aHall Effect sensor.